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2005-06-17
Theory of spin-polarized transport in ferromagnet-semiconductor structures: Unified description of ballistic and diffusive transport
A theory of spin-polarized electron transport in ferromagnet-semiconductor heterostructures, based on a unified semiclassical description of ballistic and diffusive transport in semiconductors, is outlined. The aim is to provide a framework for studying the interplay of spin relaxation and transport mechanism in spintr...
0506441v1
2006-02-06
Non-collinear Magnetoelectronics
The electron transport properties of hybrid ferromagnetic|normal metal structures such as multilayers and spin valves depend on the relative orientation of the magnetization direction of the ferromagnetic elements. Whereas the contrast in the resistance for parallel and antiparallel magnetizations, the so-called Giant ...
0602151v1
2006-02-27
Relating supercooling and glass-like arrest of kinetics for phase separated systems: studies on doped CeFe$_2$ and (La,Pr,Ca)MnO$_3$
Coexisting ferromagnetic and antiferromagnetic phases over a range of temperature as well as magnetic field have been reported in many materials of current interest, showing disorder-broadened 1st order transitions. Anomalous history effects observed in magnetization and resistivity are being explained invoking the con...
0602627v1
2006-06-09
The magnetotransport properties of La0.7Sr0.3MnO3/BaTiO3 superlattices grown by pulsed laser deposition technique
We have investigated the magnetotransport properties of La0.7Sr0.3MnO3/BaTiO3 superlattices, grown on SrTiO3 substrate by pulsed laser deposition technique, both with current-in-plane and current-perpendicular-to-the-plane directions. Several features indicate the presence of magnetic inhomogeneities at the interfaces ...
0606232v1
2006-06-30
Synthesis of VO_2 Nanowire and Observation of the Metal-Insulator Transition
We have fabricated crystalline nanowires of VO_2 using a new synthetic method. A nanowire synthesized at 650^oC shows the semiconducting behavior and a nanowire at 670^oC exhibits the first-order metal-insulator transition which is not the one-dimensional property. The temperature coefficient of resistance in the semic...
0606793v1
2006-11-17
Evolution in Materio: Exploiting the Physics of Materials for Computation
We describe several techniques for using bulk matter for special purpose computation. In each case it is necessary to use an evolutionary algorithm to program the substrate on which the computation is to take place. In addition, the computation comes about as a result of nearest neighbour interactions at the nano- micr...
0611462v1
2006-12-23
Magnetic phase diagram of Ce2Fe17
Rare-earth-based permanent-magnet materials rich in iron have relatively low ferromagnetic ordering temperatures. This is believed to be due to the presence of antiferromagnetic exchange interactions, besides the ferromagnetic interactions responsible for the magnetic order. The magnetic properties of Ce2Fe17 are anoma...
0612603v1
2006-05-06
Radiation enhancement and radiation suppression by a left-handed metamaterial
The perfect lens property of a dispersive and lossy left-handed metamaterial (LHM) disk is exploited to superimpose a source of electromagnetic radiation onto its mirror image, formed as a result of reflection from a perfect electric conductor (PEC) or a perfect magnetic conductor (PMC). The superposition of a vertical...
0605055v1
2006-07-25
Superconductivity: coherent "tunnelling" by a dielectric array of charge-carriers
Superconduction manifests when a steady-state current flows through a material without an electric field being present. It is argued here that the absence of scattering of the charge-carriers, although absolutely necessary, is not sufficient to explain why an electric field is zero when a current flows between two cont...
0607227v1
2005-04-05
Reduction of Magnetic Noise in Atom Chips by Material Optimization
We discuss the contribution of the material type in metal wires to the electromagnetic fluctuations in magnetic microtraps close to the surface of an atom chip. We show that significant reduction of the magnetic noise can be achieved by replacing the pure noble metal wires with their dilute alloys. The alloy compositio...
0504027v2
2007-04-20
Transport measurements across a tunable potential barrier in graphene
The peculiar nature of electron scattering in graphene is among many exciting theoretical predictions for the physical properties of this material. To investigate electron scattering properties in a graphene plane, we have created a gate-tunable potential barrier within a single-layer graphene sheet. We report measurem...
0704.2626v2
2007-05-16
Ab initio estimate of temperature dependence of electrical conductivity in a model amorphous material: hydrogenated amorphous silicon
We present an ab initio calculation of the DC conductivity of amorphous silicon and hydrogenated amorphous silicon. The Kubo-Greenwood formula is used to obtain the DC conductivity, by thermal averaging over extended dynamical simulation. Its application to disordered solids is discussed. The conductivity is computed f...
0705.2384v3
2007-07-08
Tensoresistive Effect in Single Crystal Microwires of Pbte Doped with Tl
Results of room temperature measurements of tensoresistive effect of thin single crystal microwires of Pb1-xTlxTe (x=0.0000 - 0.0025, d = 5 - 20 micrometers) obtained from the melted compound of corresponding composition by the filling of quartz capillary with the following crystallization of material are presented. Fo...
0707.1124v1
2007-08-13
Orbital Ordering Structures in (Nd,Pr)0.5Sr0.5MnO3 Manganite Thin Films on Perovskite (011) Substrates
Structural study of orbital-ordered manganite thin films has been conducted using synchrotron radiation, and a ground state electronic phase diagram is made. The lattice parameters of four manganite thin films, Nd0.5Sr0.5MnO3 (NSMO) or Pr0.5Sr0.5MnO3 (PSMO) on (011) surfaces of SrTiO3 (STO) or [(LaAlO3){0.3}(SrAl0.5Ta0...
0708.1693v1
2007-08-16
The nanostructural origin of the ac conductance in dielectric granular metals: the case study of Co_20(ZrO_2)_80
We show which is the nanostructure required in granular Co20(ZrO2)80 thin films to produce an ac response such as the one that is universally observed in a very wide variety of dielectric materials. A bimodal size distribution of Co particles yields randomly competing conductance channels which allow both thermally ass...
0708.2140v1
2007-08-16
Spin-transfer torques in anti-ferromagnetic metals from first principles
In spite of the absence of a macroscopic magnetic moment, an anti-ferromagnet is spin-polarized on an atomic scale. The electric current passing through a conducting anti-ferromagnet is polarized as well, leading to spin-transfer torques when the order parameter is textured, such as in anti-ferromagnetic non-collinear ...
0708.2143v2
2007-12-11
Frequency- and electric-field-dependent conductivity of single-walled carbon nanotube networks of varying density
We present measurements of the frequency and electric field dependent conductivity of single walled carbon nanotube(SWCNT) networks of various densities. The ac conductivity as a function of frequency is consistent with the extended pair approximation model and increases with frequency above an onset frequency $\omega_...
0712.1733v3
2007-12-21
Kinks in the electronic specific heat
We find that the heat capacity of a strongly correlated metal presents striking changes with respect to Landau Fermi liquid theory. In contrast with normal metals, where the electronic specific heat is linear at low temperature (with a T^3 term as a leading correction), a dynamical mean-field study of the correlated Hu...
0712.3723v2
2008-01-07
Utility of transient testing to characterize thermal interface materials
This paper analyzes a transient method for the characterization of low-resistance thermal interfaces of microelectronic packages. The transient method can yield additional information about the package not available with traditional static methods at the cost of greater numerical complexity, hardware requirements, and ...
0801.1009v1
2008-03-05
Giant room temperature piezoresistance in a metal/silicon hybrid
Metal/semiconductor hybrids are artificially created structures presenting novel properties not exhibited by either of the component materials alone. Here we present a giant piezoresistance effect in a hybrid formed from silicon and aluminum. The maximum piezoresistive gage factor (GF) of 843, measured at room temperat...
0803.0655v1
2008-04-02
Physical properties of the new Uranium ternary compounds U3Bi4M3 (M=Ni, Rh)
We report the properties of two new isostructural compounds, U3Bi4Ni3 and U3Bi4Rh3. The first of these compounds is non-metallic, and the second is a nearly ferromagnetic metal, both as anticipated from their electron count relative to other U-based members of the larger 3-4-3 family. For U3Bi4Rh3, a logarithmic increa...
0804.0393v1
2008-11-19
Intrinsic Response of Graphene Vapor Sensors
Graphene is a purely two-dimensional material that has extremely favorable chemical sensor properties. It is known, however, that conventional nanolithographic processing typically leaves a resist residue on the graphene surface, whose impact on the sensor characteristics of the system has not yet been determined. Here...
0811.3091v1
2009-03-19
Superconductivity at 17 K in (Fe2P2)(Sr4Sc2O6): a new superconducting layered pnictide oxide with a thick perovskite oxide layer
A new layered oxypnictide (Fe2P2)(Sr4Sc2O6) have been synthesized by solid-state reaction. This material has an alternating layer stacking structure of anti-fluorite Fe2P2 and perovskite-based Sr4Sc2O6 oxide layers. Space group of the material is P4/nmm and lattice constants a and c are 4.016 A and 15.543 A, respective...
0903.3314v3
2009-05-27
Precision Cutting and Patterning of Graphene with Helium Ions
We report nanoscale patterning of graphene using a helium ion microscope configured for lithography. Helium ion lithography is a direct-write lithography process, comparable to conventional focused ion beam patterning, with no resist or other material contacting the sample surface. In the present application, graphene ...
0905.4407v2
2009-06-08
Tunneling electroresistance effect in ferroelectric tunnel junctions at the nanoscale
Stable and switchable polarization of ferroelectric materials opens a possibility to electrically control their functional behavior. A particularly promising approach is to employ ferroelectric tunnel junctions where the polarization reversal in a ferroelectric barrier changes the tunneling current across the junction....
0906.1521v1
2009-06-30
Electric field effects, Mott insulator, Surface patterning, Scanning tunneling microscopy, Transition metal chalcogenides
We report the first experimental evidence for a strong electromechanical coupling in the Mott insulator GaTa4Se8 allowing a highly reproducible nano-writing with a Scanning Tunneling Microscope (STM). The local electric field across the STM junction is observed to have a threshold value above which the clean (100) surf...
0906.5473v1
2009-11-30
Kondo-like behaviors in magnetic and thermal properties of single crystal Tm5Si2Ge2
We grew the single crystal of stoichiometric Tm5Si2.0Ge2.0 using a Bridgeman method and performed XRD, EDS, magnetization, ac and dc magnetic susceptibilities, specific heat, electrical resistivity and XPS experiments. It crystallizes in orthorhombic Sm5Ge4-type structure. The mean valence of Tm ions in Tm5Si2.0Ge2.0 i...
0911.5640v1
2009-12-05
Theory and Simulation of Spin Transport in Antiferromagnetic Semiconductors: Application to MnTe
We study in this paper the parallel spin current in an antiferromagnetic semiconductor thin film where we take into account the interaction between itinerant spins and lattice spins. The spin model is an anisotropic Heisenberg model. We use here the Boltzmann's equation with numerical data on cluster distribution obtai...
0912.0989v4
2010-05-14
Effect of phonon dispersion on thermal conduction across Si/Ge interfaces
We report finite-volume simulations of the phonon Boltzmann transport equation (BTE) for heat conduction across the heterogeneous interfaces in SiGe superlattices. The diffuse mismatch model incorporating phonon dispersion and polarization is implemented over a wide range of Knudsen numbers. The results indicate that t...
1005.2578v1
2010-07-22
Anisotropic weakly localized transport in nitrogen-doped ultrananocrystalline diamond films
We establish the dominant effect of anisotropic weak localization (WL) in three dimensions associated with a propagative Fermi surface, on the conductivity correction in heavily nitrogen doped ultrananocrystalline diamond (UNCD) films based on magneto-resistance studies at low temperatures. Also, low temperature electr...
1007.3918v2
2010-09-01
Anomalous scattering in superconducting indium-doped tin telluride
Results of resistivity, Hall effect, magnetoresistance, susceptibility and heat capacity measurements are presented for single crystals of indium-doped tin telluride with compositions Sn$_{.988-x}$In$_x$Te where $0 \leq x \leq 8.4 %$, along with microstructural analysis based on transmission electron microscopy. For sm...
1009.0090v1
2010-09-06
Understanding adhesion at as-deposited interfaces from ab initio thermodynamics of deposition growth: thin-film alumina on titanium carbide
We investigate the chemical composition and adhesion of chemical vapour deposited thin-film alumina on TiC using and extending a recently proposed nonequilibrium method of ab initio thermodynamics of deposition growth (AIT-DG) [Rohrer J and Hyldgaard P 2010 Phys. Rev. B 82 045415]. A previous study of this system [Rohr...
1009.1027v1
2010-09-07
Phase coherent transport in SrTiO3/LaAlO3 interfaces
The two dimensional electron gas formed between the two band insulators SrTiO3 and LaAlO3 exhibits a variety of interesting physical properties which make it an appealing material for use in future spintronics and/or quantum computing devices. For this kind of applications electrons have to retain their phase memory fo...
1009.1273v1
2010-10-11
Restoring the electrical conductivity of graphene oxide films by UV light induced oxygen desorption
We report a chemical free method for the reduction of graphene oxide (GO) thin films. It was observed how for GO films annealed in air the oxygen species desorb from the GO surface upon exposure to UV light and how the surface resistivity of such deoxygenated GO films decreases with increasing the exposure to the UV li...
1010.2108v4
2010-11-12
Memory effects in complex materials and nanoscale systems
Memory effects are ubiquitous in nature and are particularly relevant at the nanoscale where the dynamical properties of electrons and ions strongly depend on the history of the system, at least within certain time scales. We review here the memory properties of various materials and systems which appear most strikingl...
1011.3053v1
2010-12-13
The split-ring Josephson resonator as an artificial atom
Using the resistive-shunted-junction model we show that a split-ring Josephson oscillator or radio-frequency SQUID in the hysteretic regime is similar to an atomic system. It has a number of stationary states that we characterize. Applying a short magnetic pulse we switch the system from one state to another. These sta...
1012.2833v1
2010-12-23
Memristive Systems Analysis of 3-Terminal Devices
Memristive systems were proposed in 1976 by Leon Chua and Sung Mo Kang as a model for 2-terminal passive nonlinear dynamical systems which exhibit memory effects. Such systems were originally shown to be relevant to the modeling of action potentials in neurons in regards to the Hodgkin-Huxley model and, more recently, ...
1012.5124v1
2011-01-14
Ni-Mn-Ga films in the austenite and the martensite structures at room temperature: Uniaxial texturation and epitaxial growth
Ni-Mn-Ga films in the austenite and the martensite structures at room temperature have been obtained using the DC magnetron sputtering technique. Two elaboration processes were studied. A first batch of samples was deposited using a resist sacrificial layer in order to release the film from the substrate before vacuum ...
1101.2811v1
2011-01-31
Yielding and irreversible deformation below the microscale: Surface effects and non-mean-field plastic avalanches
Nanoindentation techniques recently developed to measure the mechanical response of crystals under external loading conditions reveal new phenomena upon decreasing sample size below the microscale. At small length scales, material resistance to irreversible deformation depends on sample morphology. Here we study the me...
1102.0019v2
2011-05-11
Linear magnetoresistance in commercial n-type silicon due to inhomogeneous doping
Free electron theory tells us that resistivity is independent of magnetic field. In fact, most observations match the semiclassical prediction of a magnetoresistance that is quadratic at low fields before saturating. However, a non-saturating linear magnetoresistance has been observed in exotic semiconductors such as s...
1105.2174v1
2011-05-27
Development of correlated quasiparticle conductance peak as molecule-linked gold nanoparticle films transition from Mott-insulator to metal phases
We have studied conductance ($\it{g}$) of butanedithiol-linked gold nanoparticle films across a percolation insulator-to-metal transition. As the transition proceeds, electrons become itinerant (i.e. Coulomb charging and kinetic effects are both significant), and films exhibit a previously unobserved zero-bias conducta...
1105.5647v1
2011-07-31
Observation of Quantized Hall Effect and Shubnikov-de Hass Oscillations in Highly Doped Bi2Se3: Evidence for Layered Transport of Bulk Carriers
Bi2Se3 is an important semiconductor thermoelectric material and a prototype topological insulator. Here we report observation of Shubnikov-de Hass (SdH) oscillations accompanied by quantized Hall resistances (Rxy) in highly-doped n-type Bi2Se3 with bulk carrier concentrations of few 10^19 cm^-3. Measurements under til...
1108.0204v2
2011-08-30
Linear magnetoresistivity in the ternary AM2B2 and A3Rh8B6 phases (A = Ca, Sr; M = Rh, Ir)
We studied the magnetoresistivity of the AM2B2 and A3Rh8B6 (A = Ca, Sr; M = Rh, Ir) compounds within the ranges 1.8<=T<=300 K and 0<=H<=50 kOe. The zero-field resistivity {\rho}0(T) is metallic and follows closely the Bloch-Gr\"uneisen description. A positive, nonsaturating, and dominantly linear-in-H magnetoresistivit...
1108.5803v1
2011-09-22
Microscopic model for the ferroelectric field effect in oxide heterostructures
A microscopic model Hamiltonian for the ferroelectric field effect is introduced for the study of oxide heterostructures with ferroelectric components. The long-range Coulomb interaction is incorporated as an electrostatic potential, solved self-consistently together with the charge distribution. A generic double-excha...
1109.4791v1
2011-10-09
Optimizing the Bi_(2-x)Sb_(x)Te_(3-y)Se_(y) solid solutions to approach the intrinsic topological insulator regime
To optimize the bulk-insulating behavior in the topological insulator materials having the tetradymite structure, we have synthesized and characterized single-crystal samples of Bi_(2-x)Sb_(x)Te_(3-y)Se_(y) (BSTS) solid solution at various compositions. We have elucidated that there are a series of "intrinsic" composit...
1110.1788v1
2011-10-24
Ni(111)|Graphene|h-BN Junctions as Ideal Spin Injectors
Deposition of graphene on top of hexagonal boron nitride (h-BN) was very recently demonstrated while graphene is now routinely grown on Ni. Because the in-plane lattice constants of graphite, h-BN, graphite-like BC2N and of the close-packed surfaces of Co, Ni and Cu match almost perfectly, it should be possible to prep...
1110.5291v1
2011-11-30
Synthesis, Characterization, and Finite Size Effects on Electrical Transport of Nanoribbons of the Charge-Density Wave Conductor NbSe3
NbSe3 exhibits remarkable anisotropy in most of its physical properties and has been a model system for studies of quasi-one-dimensional charge-density-wave (CDW) phenomena. Herein, we report the synthesis, characterization, and electrical transport of single-crystalline NbSe3 nanoribbons by a facile one-step vapour tr...
1112.0039v1
2012-04-02
Phase Stability, Structures and Properties of the (Bi2)m(Bi2Te3)n Natural Superlattices
The phase stability of the (Bi2)m(Bi2Te3)n natural superlattices has been investigated through the low temperature solid state synthesis of a number of new binary BixTe1-x compositions. Powder X-ray diffraction revealed that an infinitely adaptive series forms for 0.44 < x < 0.70, while an unusual 2-phase region with c...
1204.0356v1
2012-05-16
Spin transport and spin dephasing in zinc oxide
The wide bandgap semiconductor ZnO is interesting for spintronic applications because of its small spin-orbit coupling implying a large spin coherence length. Utilizing vertical spin valve devices with ferromagnetic electrodes (TiN/Co/ZnO/Ni/Au), we study the spin-polarized transport across ZnO in all-electrical experi...
1205.3666v3
2012-05-28
Visualizing Landau levels of Dirac electrons in a one dimensional potential
Using scanning tunneling spectroscopy we have measured the response of Dirac electrons in a magnetic field to the presence of a well-defined smoothly varying 1D periodic potential. We find that the lower index Landau level energies reliably trace the potential variations, while the higher index levels appear surprising...
1205.6230v2
2012-07-14
Topological phase transition induced by random substitution
The transition from topologically nontrivial to a trivial state is studied by first-principles calculations on bulk zinc-blende type (Hg$_{1-x}$Zn$_x$)(Te$_{1-x}$S$_x$) disordered alloy series. The random chemical disorder was treated by means of the Coherent Potential Approximation. We found that although the phase tr...
1207.3463v1
2012-07-23
Superconducting and thermoelectric properties of new layered Superconductor Bi4O4S3
Polycrystalline sample of the new layered superconductor Bi4O4S3 is successfully synthesized by solid-state reaction method by using Bi, S and Bi2O3 powders with one step reaction. The superconducting transition temperature (Tconset=4.5 K), the zero resistance transition temperature (Tc0=4.07 K) and the diamagnetic tra...
1207.5395v1
2012-09-13
Topological-Metal to Band-Insulator Transition in (Bi1-xInx)2Se3 Thin Films
By combining transport and photo emission measurements on (Bi1-xInx)2Se3 thin films, we report that this system transforms from a topologically non-trivial metal into a topologically trivial band insulator through three quantum phase transitions. At x = 3-7%, there is a transition from a topologically non-trivial metal...
1209.2840v1
2012-11-01
Spin Hall Magnetoresistance Induced by a Non-Equilibrium Proximity Effect
We report anisotropic magnetoresistance in Pt|Y3Fe5O12 bilayers. In spite of Y3Fe5O12 being a very good electrical insulator, the resistance of the Pt layer reflects its magnetization direction. The effect persists even when a Cu layer is inserted between Pt and Y3Fe5O12, excluding the contribution of induced equilibri...
1211.0098v1
2012-11-07
Tuning the thermoelectric properties of SrTiO3 by controlled oxygen doping
We report the thermoelectric properties (Seebeck coefficient, thermal conductivity, and electrical resistivity) of lightly doped single crystals of (001)-oriented SrTiO3 (STO). Hall effect measurements show that electron doping around 10^-5 carriers per unit cell can be achieved by vacuum annealing of the crystals unde...
1211.1615v1
2012-12-21
Multigap RPC for PET: development and optimisation of the detector design
Transforming the resistive plate chambers from charged-particle into gamma-quanta detectors opens the way towards their application as a basic element of a hybrid imaging system, which combines positron emission tomography (PET) with magnetic resonance imaging (MRI) in a single device and provides non- and minimally- i...
1212.5551v1
2013-02-18
Comparative Measurements of Inverse Spin Hall and Magnetoresistance in YIG|Pt and YIG|Ta
We report on a comparative study of spin Hall related effects and magnetoresistance in YIG|Pt and YIG|Ta bilayers. These combined measurements allow to estimate the characteristic transport parameters of both Pt and Ta layers juxtaposed to YIG: the spin mixing conductance $G_{\uparrow \downarrow}$ at the YIG$|$normal m...
1302.4416v1
2013-02-20
Anomalous metallic state above the upper critical field of the conventional three-dimensional superconductor AgSnSe2 with strong intrinsic disorder
We report superconducting properties of AgSnSe2 which is a conventional type-II superconductor in the very dirty limit due to intrinsically strong electron scatterings. While this material is an isotropic three-dimensional (3D) superconductor with a not-so-short coherence length where strong vortex fluctuations are NOT...
1302.4787v1
2013-03-06
Li$_2$RhO$_3$: A spin-glassy relativistic Mott insulator
Motivated by the rich interplay among electronic correlation, spin-orbit coupling (SOC), crystal-field splitting, and geometric frustrations in the honeycomb-like lattice, we systematically investigated the electronic and magnetic properties of Li$_2$RhO$_3$. The material is semiconducting with a narrow band gap of $\D...
1303.1235v2
2013-06-13
Combinatorial search of superconductivity in Fe-B composition spreads
We have fabricated Fe-B thin film composition spreads in search of possible superconducting phases following a theoretical prediction by Kolmogorov et al.^1 Co-sputtering was used to deposit spreads covering a large compositional region of the Fe-B binary phase diagram. A trace of superconducting phase was found in the...
1306.3024v1
2013-07-16
Correlating toughness and roughness in ductile fracture
Three dimensional calculations of ductile crack growth under mode I plane strain, small scale yielding conditions are carried out using an elastic-viscoplastic constitutive relation for a progres- sively cavitating plastic solid with two populations of void nucleating second phase particles. Full field solutions are ob...
1307.4413v1
2013-08-30
A linear nonequilibrium thermodynamics approach to optimization of thermoelectric devices
Improvement of thermoelectric systems in terms of performance and range of applications relies on progress in materials science and optimization of device operation. In this chapter, we focuse on optimization by taking into account the interaction of the system with its environment. For this purpose, we consider the il...
1308.6735v1
2013-09-24
Efficient Gate-tunable light-emitting device made of defective boron nitride nanotubes: from ultraviolet to the visible
Boron nitride is a promising material for nanotechnology applications due to its two-dimensional graphene-like, insulating, and highly-resistant structure. Recently it has received a lot of attention as a substrate to grow and isolate graphene as well as for its intrinsic UV lasing response. Similar to carbon, one-dime...
1309.6117v1
2013-10-11
Dropping the Ball: The effect of anisotropic granular materials on ejecta and impact crater shape
In this fluid dynamics video, we present an experimental investigation of the shape of impact craters in granular materials. Complex crater shapes, including polygons, have been observed in many terrestrial planets as well as moons and asteroids. We release spherical projectiles from different heights above a granular ...
1310.3290v1
2013-10-20
Impurity effects in Cu$_2$O
The doping of wide gap semiconductors is an interesting problem both from the scientific and technological point of view. A well known example of this problem is the doping of Cu$_2$O. The only element which has produced an order of magnitude increase in the conductivity of Cu$_2$O bulk samples is chlorine, as previous...
1310.5341v1
2013-11-07
Magnetic domain and magnetic resistance phase transition in strongly correlated electronic material of perovskites junction
The junction magnetoresistivity and domain phase transition were studied between ZnO and La0.4Gd0.1Sr0.5CoO3 thin films grown on LaAlO3 (100) substrates epitaxially by pulse laser deposit. The ferromagnetic transformation into phase-separated (two phase) state was displayed below Tc~127 and has observed that the lattic...
1311.1650v1
2013-11-17
First-principle study of octahedral tilting and Ferroelectric like transition in metallic LiOsO3
The octahedral tilting and ferroelectric-like structural transition of LiOsO3 metallic perovskite [Nature Materials 12, 1024 (2013)] was examined using first-principles density-functional theory. In LiOsO3, a-a-a- octahedral titling mode is responsible for the cubic to rhombohedral structural transition, which is stabl...
1311.4139v1
2014-02-24
Experimental realization of a semiconducting full Heusler compound: Fe2TiSi
Single-phase films of the full Heusler compound Fe2TiSi have been prepared by magnetron sputtering. The compound is found to be a semiconductor with a gap of 0.4eV. The electrical resistivity has a logarithmic temperature dependence up to room temperature due to Kondo scattering of a dilute free electron gas off superp...
1402.5755v1
2014-03-12
Magnetoresistance of double layer hybrid system in tilted magnetic field
Magnetoresistance and Hall coefficient of a graphene layer are investigated in the presence of a tilted magnetic field. We consider the graphene layer is assembled by either another graphene layer or a two-dimensional electron gas (2DEG) and an interlayer electron-electron interaction is modeled within Random Phase App...
1403.2857v2
2014-03-28
Doping nature of native defects in 1T-TiSe2
The transition metal dichalcogenide 1T-TiSe2 is a quasi two-dimensional layered material with a charge density wave (CDW) transition temperature of TCDW 200 K. Self-doping effects for crystals grown at different temperatures introduce structural defects, modify the temperature dependent resistivity and strongly perturb...
1403.7339v2
2014-04-08
Modulation of pure spin currents with a ferromagnetic insulator
We propose and demonstrate spin manipulation by magnetically controlled modulation of pure spin currents in cobalt/copper lateral spin valves, fabricated on top of the magnetic insulator Y$_3$Fe$_5$O$_{12}$ (YIG). The direction of the YIG magnetization can be controlled by a small magnetic field. We observe a clear mod...
1404.2311v2
2014-04-10
Tunable chiral spin texture in magnetic domain-walls
Magnetic domain-walls (DWs) with a preferred chirality exhibit very efficient current-driven motion. Since structural inversion asymmetry (SIA) is required for their stability, the observation of chiral domain walls in highly symmetric Pt/Co/Pt is intriguing. Here, we tune the layer asymmetry in this system and observe...
1404.2945v1
2014-04-17
Extreme thermopower anisotropy and interchain transport in the quasi-one-dimensional metal Li(0.9)Mo(6)O(17)
Thermopower and electrical resistivity measurements transverse to the conducting chains of the quasi-one-dimensional metal Li(0.9)Mo(6)O(17) are reported in the temperature range 5 K <= T <= 500 K. For T>= 400 K the interchain transport is determined by thermal excitation of charge carriers from a valence band ~ 0.14 e...
1404.4576v3
2014-05-15
Damage nucleation from repeated dislocation absorption at a grain boundary
Damage nucleation from repeated dislocation absorption at a grain boundary is simulated with molecular dynamics. At the grain boundary-dislocation intersection site, atomic shuffling events determine how the free volume brought by the incoming dislocation is accommodated. This process in turn determines the crack nucle...
1405.3974v2
2014-06-04
Magnetic-Field Induced Semimetal in Topological Crystalline Insulator Thin Films
We investigate electromagnetic properties of a topological crystalline insulator (TCI) thin film under external electromagnetic fields. The TCI thin film is a topological insulator indexed by the mirror-Chern number. It is demonstrated that the gap closes together with the emergence of a pair of gapless cones carrying ...
1406.1009v2
2014-06-05
Magnetotransport in ferromagnetic Mn5Ge3, Mn5Ge3C0.8, and Mn5Si3C0.8 thin films
The electrical resistivity, anisotropic magnetoresistance (AMR), and anomalous Hall effect of ferromagnetic Mn5Ge3, Mn5Ge3C0.8, and Mn5Si3C0.8 thin films has been investigated. The data show a behavior characteristic for a ferromagnetic metal, with a linear increase of the anomalous Hall coefficient with Curie temperat...
1406.1442v1
2014-07-16
Mesoscale Imperfections in MoS2 Atomic Layers Grown by Vapor Transport Technique
The success of isolating small flakes of atomically thin layers through mechanical exfoliation has triggered enormous research interest in graphene and other two-dimensional materials. For device applications, however, controlled large-area synthesis of highly crystalline monolayers with a low density of electronically...
1407.4188v1
2014-07-30
Synthesis and transport properties of ternary type-I Si clathrate K8Al7Si39
A ternary type-I Si clathrate, K8AlxSi46-x, which is a candidate functional material composed of abundant non-toxic elements, was synthesized and its transport properties were investigated at temperatures ranging from 10 to 320 K. The synthesized compound is confirmed to be the ternary type-I Si clathrate K8Al7Si39 wit...
1407.7911v2
2014-08-30
Chemical Pressure effect at the boundary of Mott insulator and itinerant electron limit of Spinel Vanadates
The chemical pressure effect on the structural, transport, magnetic and electronic properties (by measuring X-ray photoemission spectroscopy) of ZnV2O4 has been investigated by doping Mn and Co on the Zinc site of ZnV2O4. With Mn doping the V-V distance increases and with Co doping it decreases. The resistivity and the...
1409.0106v1
2014-12-23
Temperature controlled motion of an antiferromagnet-ferromagnet interface within a dopant-graded FeRh epilayer
Chemically ordered B2 FeRh exhibits a remarkable antiferromagnetic-ferromagnetic phase transition that is first order. It thus shows phase coexistence, usually by proceeding though nucleation at random defect sites followed by propagation of phase boundary domain walls. The transition occurs at a temperature that can b...
1412.7346v1
2015-01-21
Efficient Linear Scaling Approach for Computing the Kubo Hall Conductivity
We report an order-N approach to compute the Kubo Hall conductivity for disorderd two-dimensional systems reaching tens of millions of orbitals, and realistic values of the applied external magnetic fields (as low as a few Tesla). A time-evolution scheme is employed to evaluate the Hall conductivity $\sigma_{xy}$ using...
1501.05100v2
2015-01-26
Raman scattering investigation of large positive magnetoresistance material WTe$_2$
We have performed polarized Raman scattering measurements on WTe$_2$, for which an extremely large positive magnetoresistance has been reported recently. We observe 5 A$_1$ phonon modes and 2 A$_2$ phonon modes out of 33 Raman active modes, with frequencies in good accordance with first-principles calculations. The ang...
1501.06321v3
2015-02-17
Superconducting Dome and Crossover to an Insulating State in [Tl4]Tl1-xSnxTe3
The structural, superconducting, and electronic phase diagram of [Tl4]Tl1-xSnxTe3 is reported. Magnetization and specific heat measurements show bulk superconductivity exists for 0 < x < 0.4. Resistivity measurements indicate a crossover from a metallic state for low dopings to a doped insulator at x = 1. Universally, ...
1502.05059v2
2015-02-24
Room temperature magnetodielectric studies on Mn doped LaGaO3
The polycrystalline samples of LaGa1-xMnxO3 (0<x<0.3) has been prepared by solid state reaction route. The phase purity of these samples has been confirmed by powder x-ray diffraction experiments carried out on BL-12 at Indus-2 synchrotron radiation source. The sample with x=0.2 shows significant change in the value of...
1502.06887v2
2015-03-18
Atomically Thin Resonant Tunnel Diodes built from Synthetic van der Waals Heterostructures
Vertical integration of two-dimensional van der Waals materials is predicted to lead to novel electronic and optical properties not found in the constituent layers. Here, we present the direct synthesis of two unique, atomically thin, multi-junction heterostructures by combining graphene with the monolayer transition-m...
1503.05592v1
2015-09-17
Microwave Loss Reduction in Cryogenically Cooled Conductors
Measurements of microwave attenuation at room temperature and 4.2 K have been performed on some conductors commonly used in receiver input circuits. The reduction in loss on cooling is substantial, particularly for copper and plated gold, both of which showed a factor of 3 loss reduction. Copper passivated with benzotr...
1509.05273v1
2015-09-17
Symmetry constraints on the elastoresistivity tensor
The elastoresistivity tensor $m_{ij,kl}$ characterizes changes in a material's resistivity due to strain. As a fourth-rank tensor, elastoresistivity can be a uniquely useful probe of the symmetries and character of the electronic state of a solid. We present a symmetry analysis of $m_{ij,kl}$ (both in the presence and ...
1509.05462v1
2015-10-19
Structure, Energy, and Thermal Transport Properties of Si-SiO$_2$ Nanostructures using an Ab initio based Parameterization of a Charge-Optimized Many-Body Forcefield
In an effort to extend the reach of current ab initio calculations to simulations requiring millions of configurations for complex systems such as heterostructures, we have parameterized the third-generation Charge Optimized Many-Body (COMB3) potential using solely ab initio total energies, forces, and stress tensors a...
1510.05416v1
2015-11-07
Anomalous magneto-elastic and charge doping effects in thallium-doped BaFe2As2
Within the BaFe2As2 crystal lattice, we partially substitute thallium for barium and report the effects of interlayer coupling in Ba1-xTlxFe2As2 crystals. We demonstrate the unusual effects of magneto-elastic coupling and charge doping in this iron-arsenide material, whereby Neel temperature rises with small x, and the...
1511.02400v1
2015-11-24
Transport and thermodynamic properties under anharmonic motion in type-I Ba8Ga16Sn30 clathrate
Anharmonic guest atom oscillation has direct connection to the thermal transport and thermo- electric behavior of type-I Ba8Ga16Sn30 clathrates. This behavior can be observed through several physical properties, with for example the heat capacity providing a measure of the overall excita- tion level structure. Localize...
1511.07594v1
2015-11-28
Extremely large magnetoresistance in few-layer graphene/boron-nitride heterostructures
Understanding magnetoresistance, the change in electrical resistance upon an external magnetic field, at the atomic level is of great interest both fundamentally and technologically. Graphene and other two-dimensional layered materials provide an unprecedented opportunity to explore magnetoresistance at its nascent sta...
1511.08867v1
2015-12-22
Large-signal model of the bilayer graphene field-effect transistor targeting radio-frequency applications: theory versus experiment
Bilayer graphene is a promising material for radio-frequency transistors because its energy gap might result in a better current saturation than the monolayer graphene. Because the great deal of interest in this technology, especially for flexible radio-frequency applications, gaining control of it requires the formula...
1512.07159v1
2016-01-21
Saturation of ion irradiation effects in Cr2AlC
Cr2AlC materials were irradiated with 7 MeV Xe26+ ions and 500 keV He2+ ions at room temperature. A structural transition with an increased c lattice parameter and a decreased a lattice parameter occurs after irradiation to doses above 1 dpa. Nevertheless, the modified structure is stable up to the dose of 5.2 dpa with...
1601.05514v1
2016-02-02
Fast synthesis of Fe1.1Se1-xTex superconductors in a self-heating and furnace-free way
A fast and furnace-free method of combustion synthesis is employed for the first time to synthesize iron-based superconductors. Using this method, Fe1.1Se1-xTex (0<=x<=1) samples can be prepared from self-sustained reactions of element powders in only tens of seconds. The obtained Fe1.1Se1-xTex samples show clear zero ...
1602.00880v1
2016-02-11
A multiscale model of distributed fracture and permeability in solids in all-round compression
We present a microstructural model of permeability in fractured solids, where the fractures are described in terms of recursive families of parallel, equidistant cohesive faults. Faults originate upon the attainment of a tensile or shear resistance in the undamaged material. Secondary faults may form in a hierarchical ...
1602.03801v2
2016-04-04
Universal scaling for the spin-electricity conversion on surface states of topological insulators
We have investigated spin-electricity conversion on surface states of bulk-insulating topological insulator (TI) materials using a spin pumping technique. The sample structure is Ni-Fe|Cu|TI trilayers, in which magnetic proximity effects on the TI surfaces are negligibly small owing to the inserted Cu layer. Voltage si...
1604.00751v1
2016-04-06
Enhanced Thermoelectric Power and Electronic Correlations in RuSe$_2$
We report the electronic structure, electric and thermal transport properties of Ru$_{1-x}$Ir$_{x}$Se$_2$ ($x \leq 0.2$). RuSe$_2$ is a semiconductor that crystallizes in a cubic pyrite unit cell. The Seebeck coefficient of RuSe$_2$ exceeds -200 $\mu$V/K around 730 K. Ir substitution results in the suppression of the r...
1604.01755v1
2016-04-12
EPW: Electron-phonon coupling, transport and superconducting properties using maximally localized Wannier functions
The EPW (Electron-Phonon coupling using Wannier functions) software is a Fortran90 code that uses density-functional perturbation theory and maximally localized Wannier functions for computing electron-phonon couplings and related properties in solids accurately and efficiently. The EPW v4 program can be used to comput...
1604.03525v2
2016-05-09
A non-volatile memory based on nonlinear magnetoelectric effects
The magnetoelectric effects in multiferroics have a great potential in creating next-generation memory devices. We conceive a new concept of non-volatile memories based on a type of nonlinear magnetoelectric effects showing a butterfly-shaped hysteresis loop. The principle is to utilize the states of the magnetoelectri...
1605.02505v1
2016-05-17
Pressure-induced gap closing and metallization of MoSe$_{2}$ and MoTe$_{2}$
Layered molybdenum dichalchogenides are semiconductors whose gap is controlled by delicate interlayer interactions. The gap tends to drop together with the interlayer distance, suggesting collapse and metallization under pressure. We predict, based on first principles calculations, that layered semiconductors 2H$_c$-Mo...
1605.05111v1