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2017-09-15
Atomic theory of viscoelastic response and memory effects in metallic glasses
An atomic-scale theory of the viscoelastic response of metallic glasses is derived from first principles, using a Zwanzig-Caldeira-Leggett system-bath Hamiltonian as a starting point within the framework of nonaffine linear response to mechanical deformation. This approach provides a Generalized-Langevin-Equation (GLE)...
1709.05290v1
2017-09-18
Focused electron beam induced deposition meets materials science
Focused electron beam induced deposition (FEBID) is a direct-write method for the fabrication of nanostructures whose lateral resolution rivals that of advanced electron lithography but is in addition capable of creating complex three-dimensional nano-architectures. Over the last decade several new developments in FEBI...
1709.05835v1
2017-09-28
High-pressure cell for simultaneous dielectric and neutron spectroscopy
In this article we report on the design, manufacture and testing of a high-pressure cell for doing simultaneous dielectric and neutron spectroscopy. This cell is a unique tool for studying dynamics on different timescales, from kilo- to picoseconds, covering universal features such as the alpha relaxation and fast vibr...
1709.09859v1
2017-11-09
Synthesis, processing and transport properties of cubic and trigonal solid solutions in the Mg-Si-Sn system
Mg-Si-Sn solid solutions have interesting and useful semiconducting properties particularly for thermoelectric applications. While cubic solid solutions have been prepared by a variety of methods, solid solutions with a trigonal crystal structure have not been reported. We employed a combination of high energy ball mil...
1711.03618v1
2017-11-20
Characterisation of p-type ZnS:Cu transparent conducting films fabricated by high-temperature pulsed laser deposition
Copper-doped zinc sulphide (ZnS:Cu) thin films were synthesized through pulsed laser ablation in an inert background gas on stationary and rotating substrates, and a comprehensive opto-electrical characterisation is presented. The Cu$_x$Zn$_{1-x}$S films demonstrated comparable conductivity and transparency to other le...
1711.07579v1
2017-12-11
Gate control of spin-polarized conductance in alloyed transition metal nano-contacts
To date, endeavors in nanoscale spintronics are dominated by the use of single-electron or single-spin transistors having at their heart a semiconductor, metallic or molecular quantum dot who's localized states are non-spin-degenerate and can be controlled by an external bias applied via a gate electrode. Adjusting the...
1712.03884v1
2017-12-12
CALPHAD modeling and ab initio calculations of the Np-U-Zr system
Phase diagram of Np-U-Zr, a key ternary alloy system of relevance for metallic nuclear fuels, is still largely undetermined. Here a thermodynamic model for the Np-U-Zr system is developed based on Muggianu extrapolation of our models for the U-Zr, Np-Zr, and Np-U binary systems, all employing the CALculation of PHAse D...
1712.04246v1
2017-12-13
Nanoscale Magnetic Behavior Localization in Exchange Strength Modulated Ferromagnets
Although ferromagnetism is in general a long-range collective phenomenon, it is possible to induce local spatial variations of magnetic properties in ferromagnetic materials. For example, systematic variation of the exchange coupling strength can be used to create systems that behave as if they are comprised of virtual...
1712.04998v2
2017-12-19
Spontaneous and mass-conserved formation of continuous Si frameworks
Controlled formation of porous silicon has been of primary importance for numerous landmark applications such as light emitting sources, sensors, actuators, drug delivery systems, and energy storage applications. Frequently explored methods to form the structures have long relied on selective etching of silicon, which ...
1712.07038v1
2018-01-02
Mechanical, optoelectronic and transport properties of single-layer Ca2N and Sr2N electrides
Electride materials offer attractive physical properties due to their loosely bound electrons. Ca2N, an electride in the two-dimensional (2D) form was successfully recently synthesized. We conducted extensive first-principles calculations to explore the mechanical, electronic, optical and transport response of single-l...
1801.01038v1
2018-01-20
Langevin dynamics with spatial correlations as a model for electron-phonon coupling
Stochastic Langevin dynamics has been traditionally used as a tool to describe non-equilibrium processes. When utilized in systems with collective modes, traditional Langevin dynamics relaxes all modes indiscriminately, regardless of their wavelength. We propose a generalization of Langevin dynamics that can capture a ...
1801.06610v2
2018-01-21
Enhanced thermoelectric performance in Ca substituted Sr3SnO
We report 45% enhancement in the thermoelectric figure of merit, ZT of Sr3SnO via Ca substitution. First-principles calculations have been performed to study the electronic and thermoelectric transport properties of Ca substituted Sr3SnO (Sr3-xCaxSnO). The effects of Ca subtitution on bandgap are studied and detailed m...
1801.06899v2
2018-03-07
Magnetoresistance in Hybrid Pt/CoFe2O4 Bilayers Controlled by Competing Spin Accumulation and Interfacial Chemical Reconstruction
Pure spin currents hold promises for an energy-friendlier spintronics. They can be generated by a flow of charge along a non-magnetic metal having a large spin-orbit coupling. It produces a spin accumulation at its surfaces, controllable by the magnetization of an adjacent ferromagnetic layer. Paramagnetic metals typic...
1803.02611v1
2018-03-08
Blurring the boundaries between topological and non-topological phenomena in dots
We investigate the electronic and transport properties of topological and trivial InAs$_{1-x}$Bi$_x$ quantum dots (QDs). By considering the rapid band gap change within valence band anticrossing theory for InAs$_{1-x}$Bi$_x$, we predicted that Bi-alloyed quantum wells become $\sim 30$meV gapped 2D topological insulator...
1803.02936v1
2018-03-09
Cosmic History and a Candidate Parent Asteroid for the Quasicrystal-bearing Meteorite Khatyrka
The unique CV-type meteorite Khatyrka is the only natural sample in which "quasicrystals" and associated crystalline Cu,Al-alloys, including khatyrkite and cupalite, have been found. They are suspected to have formed in the early Solar System. To better understand the origin of these exotic phases, and the relationship...
1803.03513v1
2018-03-10
Observation of Chiral character deep in the topological insulating regime in Bi$_{1-x}$Sb$_x$
Bi$_{1-x}$Sb$_x$ is a topological insulator (TI) for $x \approx 0.03 $--$0.20$. Close to the Topological phase transition at $x = 0.03$, a magnetic field induced Weyl semi-metal (WSM) state is stabilized due to the splitting of the Dirac cone into two Weyl cones of opposite chirality. A signature of the Weyl state is t...
1803.03825v1
2018-03-11
Void growth and coalescence in irradiated copper under deformation
A decrease of fracture toughness of irradiated materials is usually observed, as reported for austenitic stainless steels in Light Water Reactors (LWRs) or copper alloys for fusion applications. For a wide range of applications (e.g. structural steels irradiated at low homologous temperature), void growth and coalescen...
1803.03983v1
2018-03-14
The use of the Rietveld method and pairs distribution function analysis to study the pressure dependence of the trigonal SnSe2 and SnS2 structure
A nanostructured trigonal SnSe2 was produced by mechanical alloying, and the effect of high-pressures up to 25.8 GPa on it was investigated. The literature reports refined structural data for SnS2 for pressures up to 20 GPa. These data were used as input data in a crystallographic software to calculate the shell struct...
1803.05430v1
2018-03-15
Diffuson contribution to anomalous Hall effect in disordered Co2FeSi thin films
A wide variation in the disorder strength, as inferred from an order of magnitude variation in the longitudinal resistivity of Co2FeSi (CFS) Huesler alloy thin films of fixed (50 nm) thickness, has been achieved by growing these films on Si(111) substrates at substrate temperatures ranging from room temperature (RT) to...
1803.05590v1
2018-05-01
Band Alignment in Quantum Wells from Automatically Tuned DFT+$U$
Band alignment between two materials is of fundamental importance for multitude of applications. However, density functional theory (DFT) either underestimates the bandgap - as is the case with local density approximation (LDA) or generalized gradient approximation (GGA) - or is highly computationally demanding, as is ...
1805.00455v1
2018-05-08
Towards 'Pt-free' Anion-Exchange Membrane Fuel Cells: Fe-Sn Carbon Nitride-Graphene 'Core-Shell' Electrocatalysts for the Oxygen Reduction Reaction
We report on the development of two new Pt-free electrocatalysts (ECs) for the oxygen reduction reaction (ORR) based on graphene nanoplatelets (GNPs). We designed the ECs with a core-shell morphology, where a GNP core support is covered by a carbon nitride (CN) shell. The proposed ECs present ORR active sites that are ...
1805.03119v1
2018-05-22
FMR-related phenomena in spintronic devices
Spintronic devices, such as non-volatile magnetic random access memories and logic devices, have attracted considerable attention as potential candidates for future high efficient data storage and computing technology. In a heavy metal or other emerging material with strong spin-orbit coupling (SOC), the charge current...
1805.08496v1
2018-05-29
The effect of energy-dependent electron scattering on thermoelectric transport in novel topological semimetal CoSi
These compounds have long been known as promising thermoelectric materials. Recently it was revealed, that they also have unconventional electronic topology. This renewed interest to the investigation of their transport properties. In order to improve theoretical description of thermoelectric transport in these compoun...
1805.11334v4
2018-06-01
Localization of phonons in mass disordered alloys - A typical medium dynamical cluster approach
The effect of disorder on lattice vibrational modes has been a topic of interest for several decades. In this work, we employ a Green's function based approach, namely the dynamical cluster approximation (DCA), to investigate phonons in mass disordered systems. Detailed benchmarks with previous exact calculations are u...
1806.00282v2
2018-06-01
Machine learning materials physics: Surrogate optimization and multi-fidelity algorithms predict precipitate morphology in an alternative to phase field dynamics
Machine learning has been effective at detecting patterns and predicting the response of systems that behave free of natural laws. Examples include learning crowd dynamics, recommender systems and autonomous mobility. There also have been applications to the search for new materials that bear relations to big data clas...
1806.00503v4
2018-06-05
Precision manufacturing of a lightweight mirror body made by selective laser melting
This article presents a new and individual way to generate opto-mechanical components by Additive Manufacturing, embedded in an established process chain for the fabrication of metal optics. The freedom of design offered by additive techniques gives the opportunity to produce more lightweight parts with improved mechan...
1806.01591v1
2018-06-07
High Performance Metallic Amorphous Magnetic Flake-based Magnetodielectric Inductors
Flake-shaped FeSi-based metallic amorphous alloy particles, having an aspect ratio as high as 175 to 1, were prepared by ball milling gas atomized amorphous powders of an effective diameter of 20 micrometers. The starting powder had a saturation magnetic flux density, Bs, of 1.5 T and a coercivity, Hc, of 94 A/m. The a...
1806.02486v2
2018-06-08
Development of next generation LLRF control system for J-PARC rapid cycling synchrotron
The low level rf (LLRF) control system for the rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) started its operation in 2007. The key functions of the LLRF control system are the dual harmonic auto voltage control, which generates superposed voltages of the fundamental accelera...
1806.03015v1
2018-06-11
Slow diffusion and long lifetime in metal halide perovskites for photovoltaics
Metal halide perovskites feature excellent absorption, emission and charge carrier transport properties. These materials are therefore very well suited for photovoltaics applications where there is a growing interest. Still, questions arise when looking at the unusual long carrier lifetime that, regarding the micrometr...
1806.04248v2
2018-06-17
Modeling tunnel field effect transistors - from interface chemistry to non-idealities to circuit level performance
We present a quasi-analytical model for Tunnel Field Effect Transistors (TFETs) that includes the microscopic physics and chemistry of interfaces and non-idealities. The ballistic band-to-band tunneling current is calculated by modifying the well known Simmons equation for oxide tunneling, where we integrate the Wentze...
1806.06331v3
2018-09-06
Limits of surface analysis of thin film compounds using LEIS
Low Energy Ion Scattering (LEIS) was employed to study the surface composition of thin films of Ru on B, C and B4C films at different stages of growth. Effects of surface segregation of C were observed. Previously unknown matrix effects were observed in these samples, expressed in the decrease of LEIS signals of Ru, B ...
1809.01918v1
2018-09-06
Combined effects of nonmetallic impurities and planned metallic dopants on grain boundary energy and strength
Most research on nanocrystalline alloys has been focused on planned doping of metals with other metallic elements, but nonmetallic impurities are also prevalent in the real world. In this work, we report on the combined effects of metallic dopants and nonmetallic impurities on grain boundary energy and strength using f...
1809.02217v3
2018-09-10
Nature of glassy magnetic state in magnetocaloric materials Dy5Pd2-xNix (x = 0 and 1) and universal scaling analysis of R5Pd2 (R = Tb, Dy and Er)
We report a systematic investigation of the magnetic and magnetocaloric properties of Dy5Pd2 and Dy5PdNi. Our study on these compounds gave evidence that they exhibit complex magnetic behaviour along with the presence of glass-like magnetic phase. Furthermore, in these compounds both second order and first order phase ...
1809.03249v1
2018-09-17
Band Structure Theory of the BCC to HCP Burgers Distortion
The Burgers distortion is a two-stage transition between body centered cubic (BCC) and hexagonal close-packed (HCP) structures. Refractory metal elements from the Sc and Ti columns of the periodic table (BCC/HCP elements) form BCC structures at high temperatures but transition to HCP at low temperatures via the Burgers...
1809.06429v1
2018-09-20
Phase components in Zr7Ni10 and Hf7Ni10 binary alloys; investigations by perturbed angular correlation spectroscopy and first principles calculations
Intermetallic compounds Zr7Ni10 and Hf7Ni10 have been studied by perturbed angular correlation (PAC) spectroscopy considering the fact that Zr7Ni10 has application as hydrogen storage material in fuel cell. In stoichiometric Zr7Ni10, the phase Zr2Ni7 is found to be dominant (~38%) while a fraction of ~25% is found for ...
1809.08114v1
2018-09-27
Self-organizing maps as a method for detecting phase transitions and phase identification
Originating from image recognition, methods of machine learning allow for effective feature extraction and dimensionality reduction in multidimensional datasets, thereby providing an extraordinary tool to deal with classical and quantum models in many-body physics. In this study, we employ a specific unsupervised machi...
1809.10419v2
2018-10-24
On the interactions of Ti${_2}$AlC, Ti${_3}$AlC${_2}$, Ti${_3}$SiC${_2}$ and Cr${_2}$AlC with palladium at 900 °C
Herein we report on the reactivity between palladium, Pd, and the MAX phases, Ti${_2}$AlC, Ti${_3}$AlC${_2}$, Ti${_3}$SiC${_2}$ and Cr${_2}$AlC. Diffusion couples of Pd/MAX were heated to 900 {\deg}C under uniaxial stress of ~20 MPa for 2, 4, and 10 h in a vacuum (<1 Pa) hot press. The diffusion couples were examined u...
1811.00098v1
2018-11-08
Mg$_{3+δ}$Sb$_x$Bi$_{2-x}$ family: A promising substitute for the start-of-art n-type thermoelectric materials near room temperature
Bi2Te3-xSex family has been the n-type start-of-the-art thermoelectric materials near room temperatures (RT) for more than half-century, which dominates the active cooling and novel waves harvesting application near RT. However, the drawbacks of brittle nature and Te-containing restrict the further applications explori...
1811.03198v2
2018-11-12
Singling out the effect of quenched disorder in the phase diagram of cuprates
We investigate the specific influence of structural disorder on the suppression of antiferromagnetic order and on the emergence of cuprate superconductivity. We single out pure disorder, by focusing on a series of Y$_{z}$Eu$_{1-z}$Ba$_2$Cu$_3$O$_{6+y}$ samples at fixed oxygen content $y=0.35$, in the range $0\le z\le 1...
1811.04668v2
2019-11-04
Enhanced upper critical field in Co-doped Ba122 superconductors by lattice defect tuning
Nanoscale defects in superconductors play a dominant role in enhancing superconducting properties through electron scattering, modulation of coherence length, and correlation with quantized magnetic flux. For iron-based superconductors (IBSCs) that are expected to be employed in high-field magnetic applications, a fund...
1911.01080v1
2019-11-05
Electron diffraction covering a wide angular range from Bragg diffraction to small-angle diffraction
We construct an electron optical system to investigate Bragg diffraction (the crystal lattice plane, $10^{-2}$-$10^{-3}$ rad) with the objective lens turned off by adjusting the current in the intermediate lenses. A crossover was located on the selected-area aperture plane. Thus, the dark-field imaging can be performed...
1911.01677v1
2019-11-05
Symmetry breaking and circular photogalvanic effect in epitaxial Cd$_x$Hg$_{1-x}$Te films
We report on the observation of symmetry breaking and the circular photogalvanic effect in Cd$_x$Hg$_{1-x}$Te alloys. We demonstrate that irradiation of bulk epitaxial films with circularly polarized terahertz radiation leads to the circular photogalvanic effect (CPGE) yielding a photocurrent whose direction reverses u...
1911.01936v1
2019-11-06
Comment on: Locally self-consistent embedding approach for disordered electronic systems
We comment on article by Yi Zhang , Hanna Terletska, Ka-Ming Tam, Yang Wang, Markus Eisenbach, Liviu Chioncel, and Mark Jarrell [Phys. Rev. B {\bf 100}, 054205 (2019)]\cite{Zhang} in which to study substitution disordered systems, they presented an embedding scheme for the locally self-consistent method. Here we show t...
1911.02553v2
2019-11-05
Ideal near-Dirac triple-point semimetal in III-V semiconductor alloys
Despite the growing interest in topological materials, the difficulty of experimentally synthesizing and integrating them with other materials has been one of the main barriers restricting access to their unique properties. Recent advances in synthesizing metastable phases of crystalline materials can help to overcome ...
1911.02560v1
2019-11-06
The role of formalism in system requirements (full version)
A major determinant of the quality of software systems is the quality of their requirements, which should be both understandable and precise. Most requirements are written in natural language, good for understandability but lacking in precision. To make requirements precise, researchers have for years advocated the use...
1911.02564v6
2019-11-07
Raman scattering studies of the lateral Mn distribution in MBE-grown Ga1-xMnxN epilayers
Recent interest in very thin single phase Ga1-xMnxN dilute magnetic layers increased needs for precise, non-destructive, and relatively fast characterization methods with key issues being the macroscopic lateral Mn distribution and the absolute values of Mn concentration x. We report on resonantly enhanced UV Raman sca...
1911.02958v1
2019-11-11
Dependence of transport coefficients of Yb(Rh$_{1-x}$Co$_x$)$_2$Si$_2$ intermetallics on temperature and cobalt concentration
Dependence of transport coefficients of the Yb(Rh$_{1-x}$Co$_x$)$_2$Si$_2$ series of alloys on temperature and cobalt concentration is explained by an asymmetric Anderson model which takes into account the exchange scattering of conduction electrons on ytterbium ions and the splitting of 4$f$-states by the crystalline ...
1911.04396v3
2019-11-13
Two-valence band electron and heat transport in monocrystalline PbTe-CdTe solid solutions with high Cd content
High quality p-type PbTe-CdTe monocrystalline alloys containing up to 10 at.$\%$ of Cd are obtained by self-selecting vapor transport method. Mid infrared photoluminescence experiments are performed to follow the variation of the fundamental energy gap as a function of Cd content. The Hall mobility, thermoelectric powe...
1911.05387v1
2019-11-19
Design of n-AlInN on p-silicon heterojunction solar cells
Aluminum Indium Nitride (AlInN) alloys offer great potential for photovoltaic devices thanks to their wide direct bandgap energy that covers the solar spectrum from 0.7 eV (InN) to 6.2 eV (AlN), and their superior resistance to high temperatures and high-energy particles. In this paper, we report the design of AlInN on...
1911.08223v1
2019-11-20
Mid-infrared polarized emission from black phosphorus light-emitting diodes
The mid-infrared (MIR) spectral range is of immense use for civilian and military applications. The large number of vibrational absorption bands in this range can be used for gas sensing, process control and spectroscopy. In addition, there exists transparency windows in the atmosphere such as that between 3.6-3.8 $\mu...
1911.09184v1
2019-11-23
On the Origin of Superconductivity at Nickel-Bismuth Interfaces
Unconventional superconductivity has been suggested to be present at the interface between bismuth and nickel in thin-film bilayers. In this work, we study the structural, magnetic and superconducting properties of sputter deposited Bi/Ni bilayers. As-grown, our films do not display a superconducting transition, howeve...
1911.10427v1
2020-01-02
Effective Theory of Superconductivity in Strongly-Coupled Amorphous Materials
A theory of phonon-mediated superconductivity in strong-coupling amorphous materials is developed based on an effective description of structural disorder and its effect on the vibrational spectrum. The theory accounts for the diffusive-like transport of vibrational excitations due to disorder-induced scattering within...
2001.00404v2
2020-01-06
Controlled introduction of defects to delafossite metals by electron irradiation
The delafossite metals PdCoO$_{2}$, PtCoO$_{2}$ and PdCrO$_{2}$ are among the highest conductivity materials known, with low temperature mean free paths of tens of microns in the best as-grown single crystals. A key question is whether these very low resistive scattering rates result from strongly suppressed backscatte...
2001.01471v1
2020-01-10
Sn-modification of Pt7/alumina model catalysts: Suppression of carbon deposition and enhanced thermal stability
An atomic layer deposition process is used to modify size-selected Pt7/alumina model catalysts by Sn addition, both before and after Pt7 cluster deposition. Surface science methods are used to probe the effects of Sn-modification on the electronic properties, reactivity, and morphology of the clusters. Sn addition, eit...
2001.03580v1
2020-01-14
2D van der Waals Nanoplatelets with Robust Ferromagnetism
We have synthesized unique colloidal nanoplatelets of the ferromagnetic two-dimensional (2D) van der Waals material CrI3 and have characterized these nanoplatelets structurally, magnetically, and by magnetic circular dichroism spectroscopy. The isolated CrI3 nanoplatelets have lateral dimensions of ~25 nm and ensemble ...
2001.04594v1
2020-01-15
Niobium doping induced mirror twin boundaries in MBE grown WSe2 monolayers
Mirror twin boundary (MTB) brings unique 1D physics and properties into two-dimensional transition metal dichalcogenides (TMDCs), but they were rarely observed in non-Mo-based TMDCs. Herein, by post-growth Nb doping, high density 4|4E-W and 4|4P-Se MTBs were introduced into molecular beam epitaxy (MBE) grown WSe2 monol...
2001.05345v1
2020-01-30
Scheil-Gulliver simulations for the design of functionally graded alloys by additive manufacturing using pycalphad
Additive manufacturing (AM), through directed energy deposition, supports planned composition changes between locations within a single component, allowing for functionally graded materials (FGMs) to be developed and fabricated. The formation of deleterious phases along a particular composition path can cause significa...
2001.11611v1
2021-07-15
Tunable Mie Resonances in the Visible Spectrum
Dielectric optical nanoantennas play an important role in color displays, metasurface holograms, and wavefront shaping applications. They usually exploit Mie resonances as supported on nanostructures with high refractive index, such as Si and TiO2. However, these resonances normally cannot be tuned. Although phase chan...
2107.07081v1
2021-07-19
Deformation Behaviour of Ion-Irradiated FeCr: A Nanoindentation Study
Understanding the mechanisms of plasticity in structural steels is essential for the operation of next-generation fusion reactors. Elemental composition, particularly the amount of Cr present, and irradiation can have separate and synergistic effects on the mechanical properties of ferritic/martensitic steels. The stud...
2107.09040v1
2021-07-20
Solid-state Janus nanoprecipitation enables amorphous-like heat conduction in crystalline Mg3Sb2-based thermoelectric materials
Solid-state precipitation can be used to tailor materials properties, ranging from ferromagnets and catalysts to mechanical strengthening and energy storage. Thermoelectric properties can be modified by precipitation to enhance phonon scattering while retaining charge-carrier transmission. Here, we uncover unconvention...
2107.09397v4
2021-07-21
Thermodynamic Stable Site for Interstitial alloy (N or O) in bcc-Refractory Metals using Density Functional Theory
Plasticity in body centered cubic (bcc) refractory metals are largely due to the stress tensor induced either by solute or thermal activation. The mechanism of the solute atom(s) residence causes instability in such metals. Earlier research have considered the mechanism of oxygen (O) or carbon (C) in tungsten (W), even...
2107.10307v1
2021-07-16
Macroscopic modeling of strain-rate dependent energy dissipation of superelastic SMAs considering destabilization of martensitic lattice
Superelastic shape-memory alloys (SMAs) are unique smart materials with a considerable energy dissipation potential for dynamic loadings with varying strain-rates. The energy dissipation depends on the latent heat generated by the austenitic-martensitic transformation and the convection of that heat. Due to the thermom...
2107.12145v1
2021-07-26
Electrically Enhanced Exchange Bias via Solid State Magneto-Ionics
Electrically induced ionic motion offers a new way to realize voltage-controlled magnetism, opening the door to a new generation of logic, sensor, and data storage technologies. Here, we demonstrate an effective approach to magneto-ionically and electrically tune exchange bias in Gd/Ni$_{1-x}$Co$_{x}$O thin films (x=0....
2107.12503v2
2021-07-28
Effect of transition metal doping on magnetic hardness of CeFe$_{12}$-based compounds
In this work, compositions of CeFe11X and CeFe10X2 with all 3d, 4d, and 5d transition metal substitutions are considered. Since many previous studies have focused on the CeFe11Ti compound, this particular compound became the starting point of our considerations and we gave it special attention. We first determined the ...
2107.13352v3
2021-07-29
Exploration of Characteristic Temperature Contributions to Metallic Glass Forming Ability
Various combinations of characteristic temperatures, such as the glass transition temperature, liquidus temperature, and crystallization temperature, have been proposed as predictions of the glass forming ability of metal alloys. We have used statistical approaches from machine learning to systematically explore a wide...
2107.14157v1
2017-04-10
Electron Mobility in Polarization-doped Al$\mathrm{_{0-0.2}}$GaN with a Low Concentration Near 10$\mathrm{^{17}}$ cm$\mathrm{^{-3}}$
In this letter, carrier transport in graded Al$\mathrm{_x}$Ga$\mathrm{_{1-x}}$N with a polarization-induced n-type doping as low as ~ 10$\mathrm{^{17}}$ cm$\mathrm{^{-3}}$ is reported. The graded Al$\mathrm{_x}$Ga$\mathrm{_{1-x}}$N is grown by metal organic chemical vapor deposition on a sapphire substrate and a unifor...
1704.03001v1
2017-04-11
A Fokker-Planck reaction model for the epitaxial growth and shape transition of quantum dots
We construct a Fokker-Planck reaction model to investigate the dynamics of the coupled epitaxial growth and shape transition process of an array of quantum dots. The Fokker-Planck reaction model is based on a coupled system of Fokker-Planck equations wherein the distribution of each island type is governed by its own F...
1704.03457v1
2017-04-13
Towards low-dimensional hole systems in Be-doped GaAs nanowires
GaAs was central to the development of quantum devices but is rarely used for nanowire-based quantum devices with InAs, InSb and SiGe instead taking the leading role. p-type GaAs nanowires offer a path to studying strongly-confined 0D and 1D hole systems with strong spin-orbit effects, motivating our development of nan...
1704.03957v1
2017-04-18
Localization landscape theory of disorder in semiconductors I: Theory and modeling
We present here a model of carrier distribution and transport in semiconductor alloys accounting for quantum localization effects in disordered materials. This model is based on the recent development of a mathematical theory of quantum localization which introduces for each type of carrier a spatial function called \e...
1704.05512v1
2017-04-18
Evidence for structural transition in crystalline tantalum pentoxide films grown by RF magnetron sputtering
We investigate the effect of annealing temperature on the crystalline structure and physical properties of tantalum-pentoxide films grown by radio frequency magnetron sputtering. For this purpose, several tantalum films were deposited and the Ta$_2$O$_5$ crystalline phase was induced by exposing the samples to heat tre...
1704.05514v1
2017-04-19
Thermal Rayleigh-Marangoni convection in a three-layer liquid-metal-battery model
The combined effects of buoyancy-driven Rayleigh-B\'{e}nard convection (RC) and surface tension-driven Marangoni convection (MC) are studied in a triple-layer configuration which serves as a simplified model for a liquid metal battery (LMB). The three-layer model consists of a liquid metal alloy cathode, a molten salt ...
1704.05825v2
2017-04-26
Anomalous lattice dynamics in a sigma-Fe60V40 alloy: Mossbauer spectroscopic study
Lattice dynamics in a sigma-Fe60V40 compound, which shows a re-entrant magnetism and orders ferromagnetic ally at ca. 170K, was investigated with the Mossbauer spectroscopy in the temperature interval of 5-300 K. Two relevant spectral parameters viz. the average center shift, <CS>, and the relative recoil-free fraction...
1704.08054v1
2017-05-25
Fast Vortex Oscillations in a Ferrimagnetic Disk near the Angular Momentum Compensation Point
We theoretically study the oscillatory dynamics of a vortex core in a ferrimagnetic disk near its angular momentum compensation point, where the spin density vanishes but the magnetization is finite. Due to the finite magnetostatic energy, a ferrimagnetic disk of suitable geometry can support a vortex as a ground state...
1705.09049v2
2017-05-26
Sub-nanometre resolution of atomic motion during electronic excitation in phase-change materials
Phase-change materials based on Ge-Sb-Te alloys are widely used in industrial applications such as nonvolatile memories, but reaction pathways for crystalline-to-amorphous phase-change on picosecond timescales remain unknown. Femtosecond laser excitation and an ultrashort x-ray probe is used to show the temporal separa...
1705.09472v1
2017-05-31
Giant barocaloric effects in natural rubber: A relevant step toward solid-state cooling
Solid-state cooling based on i-caloric effects has shown to be a promising alternative to the conventional refrigeration devices. Only very recently, the research on barocaloric materials is receiving a deal of attention due to the demonstration of giant barocaloric effects in shape-memory alloys. Regarding polymers, t...
1705.10914v4
2018-06-29
High quality cobalt ferrite ultrathin films with large inversion parameter grown in epitaxy on Ag(001)
Cobalt ferrite ultrathin films with inverse spinel structure are among the best candidates for spin-filtering at room temperature. We have fabricated high-quality epitaxial ultrathin CoFe2O4 layers on Ag(001) following a three-step method: an ultrathin metallic CoFe2 alloy was first grown in coherent epitaxy on the sub...
1807.00060v1
2018-07-03
An Inside Look at the Ti-MoS2 Contact in Ultra-thin Field Effect Transistor with Atomic Resolution
Two-dimensional molybdenum disulfide (MoS2) is an excellent channel material for ultra-thin field effect transistors. However, high contact resistance across the metal-MoS2 interface continues to limit its widespread realization. Here, using atomic-resolution analytical scanning transmission electron microscopy (STEM) ...
1807.01377v1
2018-07-16
The effect of magnetism and temperature on the stability of Cr, V, Al carbide MAX phases
The stability of Cr, V, Al carbide MAX phases, materials of interest for a variety of magnetic as well as high temperature applications, has been studied using density-functional-theory first-principles calculations. The enthalpy of mixing predicts these alloys to be unstable towards unmixing at 0 K. The calculations a...
1807.05809v1
2018-07-20
Anharmonic stabilization and lattice heat transport in rocksalt $β$-GeTe
Peierls-Boltzmann transport equation, coupled with third-order anharmonic lattice dynamics calculations, has been widely used to model lattice thermal conductivity ($\kappa_{l}$) in bulk crystals. However, its application to materials with structural phase transition at relatively high temperature is fundamentally chal...
1807.08012v2
2018-10-02
Ferroelastic twin reorientation mechanisms in shape memory alloys elucidated with 3D X-ray microscopy
Three-dimensional (3D) X-ray diffraction methods were used to analyze the evolution of the load-induced rearrangements of monoclinic twin microstructures within bulk nickel-titanium specimens in 3D and across six orders of magnitude in length scales: changes in lattice plane spacings and orientations at the nanoscale, ...
1810.01493v2
2018-10-03
Influence of drying temperature on morphology of MAPbI$_3$ thin films and the performance of solar cells
Photoelectric conversion efficiency of organic-inorganic perovskite solar cells has been rapidly raised and attracted great attention in recent years. The quality of perovskite films is vital for the performance of devices. We used the anti-solvent method to prepare CH$_3$NH$_3$PbI$_3$ thin films by spin coating and dr...
1810.01907v1
2018-10-05
UHV-CVD Growth of High Quality GeSn Using SnCl4: From Growth Optimization to Prototype Devices
The persistent interest of the epitaxy of group IV alloy GeSn is mainly driven by the demand of efficient light source that could be monolithically integrated on Si for mid-infrared Si photonics. For chemical vapor deposition of GeSn, the exploration of parameter window is difficult from the beginning due to its non-eq...
1810.02523v1
2018-10-05
Effect of impurities on morphology and growth mode of (111) and (001) epitaxial-like ScN films
ScN material is an emerging semiconductor with an indirect bandgap. It has attracted attention for its thermoelectric properties, use as seed layers, and for alloys for piezoelectric application. ScN or other transition metal nitride semiconductors used for their interesting electrical properties are sensitive to conta...
1810.02593v1
2018-10-25
Electrical and Optical Properties of Heavily Ge-Doped AlGaN
We report the effect of germanium as n-type dopant on the electrical and optical properties of AlxGa1-xN layers grown by plasma assisted molecular-beam epitaxy. The Al content has been varied from x = 0 to 0.66, confirmed by Rutherford backscattering spectrometry, and the Ge concentration was increased up to [Ge] = 1E2...
1810.11108v3
2019-01-07
Unconventional magnetization textures and domain-wall pinning in Sm-Co magnets
The most powerful magnets for high temperature applications are Sm-Co-based alloys with a microstructure that combines magnetically soft and hard regions. The microstructure consists of a dense domain-wall-pinning network that endows the material with remarkable magnetic hardness. A precise understanding of the couplin...
1901.01922v3
2019-01-08
High entropy oxides: An emerging prospect for magnetic rare earth - transition metal perovskites
It has been shown that oxide ceramics containing multiple transition and/or rare-earth elements in equimolar ratios have a strong tendency to crystallize in simple single phase structures, stabilized by the high configurational entropy. In analogy to the metallic alloy systems, these oxides are denoted high entropy oxi...
1901.02395v2
2019-01-12
Rayleigh-Bénard convection with a melting boundary
We study the evolution of a melting front between the solid and liquid phases of a pure incompressible material where fluid motions are driven by unstable temperature gradients. In a plane layer geometry, this can be seen as classical Rayleigh-B\'enard convection where the upper solid boundary is allowed to melt due to...
1901.03847v1
2019-01-15
Diluted Oxide Interfaces with Tunable Ground States
The metallic interface between two oxide insulators, such as LaAlO3/SrTiO3 (LAO/STO), provides new opportunities for electronics and spintronics. However, due to the presence of multiple orbital populations, tailoring the interfacial properties such as the ground state and metal-insulator transitions remains challengin...
1901.04776v1
2019-01-16
Circumstellar CO in metal-poor stellar winds: the highly irradiated globular cluster star 47 Tucanae V3
We report the first detection of circumstellar CO in a globular cluster. Observations with ALMA have detected the CO J=3-2 and SiO v=1 J=8-7 transitions at 345 and 344 GHz, respectively, around V3 in 47 Tucanae (NGC 104; [Fe/H] = -0.72 dex), a star on the asymptotic giant branch. The CO line is detected at 7 sigma at a...
1901.05416v1
2019-01-24
A Single Pair of Weyl Fermions in Half-metallic EuCd2As2 Semimetal
An ideal Weyl semimetal with a single pair of Weyl points (WPs) may be generated by splitting a single Dirac point (DP) through the breaking of time-reversal symmetry by magnetic order. However, most known Dirac semimetals possess a pair of DPs along an axis that is protected by crystalline symmetry. Here, we demonstra...
1901.08234v2
2019-03-30
Polarizable Potentials For Metals: The Density Readjusting Embedded Atom Method (DR-EAM)
In simulations of metallic interfaces, a critical aspect of metallic behavior is missing from the some of the most widely used classical molecular dynamics force fields. We present a modification of the embedded atom method (EAM) which allows for electronic polarization of the metal by treating the valence density arou...
1904.00263v1
2019-04-04
Generation of ground state structures and electronic properties of ternary Al$_x$Ti$_y$Ni$_z$ clusters (x+y+z=6) with a two-stage DFT global search approach
The structural and electronic properties of ternary AlxTiyNiz clusters, where x, y, and z are integers and x + y + z = 6 are investigated. Both SVWN and B3LYP exchange-correlation functionals are employed in a two-stage density functional theory (DFT) calculations to generate these clusters. In the first stage, a minim...
1904.03021v2
2019-04-10
Optical excitation of propagating magnetostatic waves in an epitaxial Galfenol film by an ultrafast magnetic anisotropy change
Using a time-resolved optically-pumped scanning optical microscopy technique we demonstrate the laser-driven excitation and propagation of spin waves in a 20-nm film of a ferromagnetic metallic alloy Galfenol epitaxially grown on a GaAs substrate. In contrast to previous all-optical studies of spin waves we employ lase...
1904.05171v2
2019-04-15
Disorder induced multifractal superconductivity in monolayer niobium dichalcogenides
The interplay between disorder and superconductivity is a subtle and fascinating phenomenon in quantum many body physics. The conventional superconductors are insensitive to dilute nonmagnetic impurities, known as the Anderson's theorem. Destruction of superconductivity and even superconductor-insulator transitions occ...
1904.07076v1
2019-04-17
Revisiting the fragile-to-strong crossover in metallic glass-forming liquids: application to Cu$_x$Zr$_x$Al$_{100-2x}$
The fragile-to-strong crossover seems to be a general feature of metallic glass-forming liquids. Here, we study the behavior of shear viscosity, diffusion coefficient and vibrational density of states for Cu$_\text{x}$Zr$_\text{x}$Al$_{\text{100-2x}}$ alloy through molecular dynamics simulations. The results reveal tha...
1904.08508v2
2019-04-30
An Atom-Probe Tomographic Study of the Compositional Trajectories During gamma(f.c.c.)/gamma-prime(L12) Phase-Separation in a Ni-Al-Cr-Re Superalloy
The compositional diffusional-trajectories for a phase separation of gamma(f.c.c.)/gamma-prime(L12) phases are studied in a quaternary Ni-10Al-8.5Cr-2Re alloy, aged at 700 deg.C for 0 to 1024 h, utilizing atom-probe tomography (APT). As the gamma-prime(L12)-precipitates grow, the enrichments of Ni, Cr, and Re and deple...
1904.13035v2
2019-07-04
Large scale ab-initio simulations of dislocations
We present a novel methodology to compute relaxed dislocations core configurations, and their energies in crystalline metallic materials using large-scale \emph{ab-intio} simulations. The approach is based on MacroDFT, a coarse-grained density functional theory method that accurately computes the electronic structure b...
1907.02604v1
2019-07-23
Electrical characteristics of vertical-geometry Schottky junction to magnetic insulator (Ga,Mn)N heteroepitaxially grown on sapphire
Schottky barrier height and the ideality factor $\eta$ are established for the first time in the single phase (Ga,Mn)N using a vertical geometry device. The material has been heteroepitaxially grown on commercially available low threading dislocation density GaN:Si template. The observed above 10M$\Omega$ resistances a...
1907.09757v1
2019-07-24
Atomic scale modeling of the thermodynamic and kinetic properties of dilute alloys driven by forced atomic relocations
Sustained external forces acting on a material provide additional mechanisms to evolve the state of the system, and these mechanisms do not necessarily obey the microscopic detailed balance. Therefore, standard methods to compute the thermodynamic and kinetic properties do not apply in such driven systems. The competit...
1907.10361v2
2019-10-02
Lifshitz tail for continuous Anderson models driven by Lévy operators
We investigate the behavior near zero of the integrated density of states $\ell$ for random Schr\"{o}dinger operators $\Phi(-\Delta) + V^{\omega}$ in $L^2(\mathbb R^d)$, $d \geq 1$, where $\Phi$ is a complete Bernstein function such that for some $\alpha \in (0,2]$, one has $ \Phi(\lambda) \asymp \lambda^{\alpha/2}$, $...
1910.01153v1