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2015-01-13
Superconductivity in efficient thermoelectric Cu$_3$Sb$_{0.98}$Al$_{0.02}$Se$_4$
Both superconductivity and thermoelectricity offer promising prospects for daily energy efficiency applications. The advancements of thermoelectric materials have led to the huge improvement of the thermoelectric figure of merit in the past decade. By applying pressure on a highly efficient thermoelectric material Cu$_...
1501.03382v1
2015-01-29
Testing Results of the Prototype Beam Absorber for the PXIE MEBT
One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H^{-} bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches o...
1501.07568v1
2015-01-31
Density-functional study of the pure and palladium doped small copper and silver clusters
The size-dependent electronic, structural, magnetic and vibrational properties of small pure cop- per and silver clusters and their alloys with one and two palladium atoms are studied by using full-potential all-electron density functional computations. The stable isomers of these clusters are identified and their theo...
1502.00107v1
2015-02-03
Disruption of Thermally-Stable Nanoscale Grain Structures by Strain Localization
Nanocrystalline metals with average grain sizes of only a few nanometers have recently been observed to fail through the formation of shear bands. Here, we investigate this phenomenon in nanocrystalline Ni which has had its grain structure stabilized by doping with W, with a specific focus on understanding how strain l...
1502.01052v2
2015-02-05
High power density test of PXIE MEBT absorber prototype
One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H- bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto...
1502.01709v1
2015-02-06
Nitrogen-Nitrogen Bonds Violate Stability of N-Doped Graphene
Two-dimensional alloys of carbon and nitrogen represent an urgent interest due to prospective applications in nanomechanical and optoelectronic devices. Stability of these chemical structures must be understood as a function of their composition. The present study employs hybrid density functional theory and reactive m...
1502.01939v1
2015-02-12
Hydrodynamic coarsening in phase-separated silicate melts
Using in-situ synchrotron tomography, we investigate the coarsening dynamics of barium borosilicate melts during phase separation. The 3-D geometry of the two interconnected phases is determined thanks to image processing. We observe a linear growth of the size of domains with time, at odds with the sublinear diffusive...
1502.03719v1
2015-02-19
Hysteresis in Magnetic Shape Memory Composites: Modeling and Simulation
Magnetic shape memory alloys are characterized by the coupling between a structural phase transition and magnetic one. This permits to control the shape change via an external magnetic field, at least in single crystals. Composite materials with single-crystalline particles embedded in a softer matrix have been propose...
1502.05608v2
2015-02-20
Existence of weak solutions for Cahn-Hilliard systems coupled with elasticity and damage
A typical phase field approach for describing phase separation and coarsening phenomena in alloys is the Cahn-Hilliard model. This model has been generalized to the so-called Cahn-Larch\'e system by combining it with elasticity to capture non-neglecting deformation phenomena, which occur during phase separation and coa...
1502.05826v1
2015-02-20
Existence of weak solutions for a PDE system describing phase separation and damage processes including inertial effects
In this paper, we consider a coupled PDE system describing phase separation and damage phenomena in elastically stressed alloys in the presence of inertial effects. The material is considered on a bounded Lipschitz domain with mixed boundary conditions for the displacement variable. The main aim of this work is to esta...
1502.05861v2
2015-02-25
Superconductivity in the presence of disorder in skutterudite-related La$_3$Co$_4$Sn$_{13}$ and La$_3$Ru$_4$Sn$_{13}$ compounds; electrical transport and magnetic studies
La$_3$Co$_4$Sn$_{13}$ and La$_3$Ru$_4$Sn$_{13}$ were categorized as BCS superconductors. In a plot of the critical field $H_{c2}$ vs $T$, La$_3$Ru$_4$Sn$_{13}$ displays a second superconducting phase at the higher critical temperature $T_c^{\star}$, characteristic of inhomogeneous superconductors, while La$_3$Co$_4$Sn$...
1502.07324v1
2015-03-15
Statistical Estimation and Clustering of Group-invariant Orientation Parameters
We treat the problem of estimation of orientation parameters whose values are invariant to transformations from a spherical symmetry group. Previous work has shown that any such group-invariant distribution must satisfy a restricted finite mixture representation, which allows the orientation parameter to be estimated u...
1503.04474v2
2015-03-16
Spin-fluctuation mechanism of anomalous temperature dependence of magnetocrystalline anisotropy in itinerant magnets
The origins of the anomalous temperature dependence of magnetocrystalline anisotropy in (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys are elucidated using first-principles calculations within the disordered local moment model. Excellent agreement with experimental data is obtained. The anomalies are associated with the changes in...
1503.04790v2
2015-03-17
Proposal to directly observe the Kondo effect through enhanced photo-induced scattering of cold fermionic and bosonic atoms
We propose an experimental protocol to directly observe the Kondo effect by scattering ultracold atoms with spin-dependent interactions. We propose using an optical Feshbach resonance to engineer Kondo-type spin-dependent interactions in a system with ultracold $^6$Li and $^{87}$Rb gases. We calculate the momentum tran...
1503.05234v3
2015-03-19
A new class of chiral materials hosting magnetic skyrmions beyond room temperature
Skyrmions, topologically protected vortex-like nanometric spin textures in magnets, have been attracting increasing attention for emergent electromagnetic responses and possible technological applications for spintronics. In particular, metallic magnets with chiral and cubic/tetragonal crystal structure may have high p...
1503.05651v1
2015-03-23
Gate-tunable high mobility remote-doped InSb/In_{1-x}Al_{x}Sb quantum well heterostructures
Gate-tunable high-mobility InSb/In_{1-x}Al_{x}Sb quantum wells (QWs) grown on GaAs substrates are reported. The QW two-dimensional electron gas (2DEG) channel mobility in excess of 200,000 cm^{2}/Vs is measured at T=1.8K. In asymmetrically remote-doped samples with an HfO_{2} gate dielectric formed by atomic layer depo...
1503.06710v1
2015-03-26
Bohr's correspondence principle for atomic transport calculations
In this work we perform a comparison between Classical Molecular Static (CMS) and quantum Density Functional Theory (DFT) calculations in order to obtain the diffusion coefficients for diluted \emph{Fe-Cr} alloys. We show that, in accordance with Bohr's correspondence principle, as the size of the atomic cell (total nu...
1503.07762v1
2015-03-27
Yield Strength as a Thermodynamic Consequence of Information Erasure
We observe that the yield strength of a variety of materials, including highly structured and densely packed metals, alloys and semi-crystalline polymers is reasonably approximated by the thermal energy density of the material. This suggests that it is related to the entropic cost of the irreversible work done during p...
1503.08114v1
2015-03-27
Direct Calculation of Modal Contributions to Thermal Conductivity via Green-Kubo Modal Analysis: Crystalline and Amorphous Silicon
In this letter we derive a new method for direct calculation of the modal contributions to thermal conductivity, which is termed Green-Kubo modal analysis (GKMA). The GKMA method combines the lattice dynamics formalism with the Green-Kubo formula for thermal conductivity, such that the thermal conductivity becomes a di...
1503.08178v1
2015-04-05
On the additive manufacturing, post-tensioning and testing of bi-material tensegrity structures
An investigation on the additive manufacturing and the experimental testing of 3D models of tensegrity prisms and columns is presented. An electron beam melting facility (Arcam EBM S12) is employed to 3D print structures composed of tensegrity prisms endowed with rigid bases and temporary supports, which are made out o...
1504.01122v1
2015-04-06
On the high-pressure superconducting phase in platinum hydride
Motivated by the ambiguous experimental data for the superconducting phase in silane (SiH$_{4}$), which may originate from the platinum hydride (PtH), we provide a theoretical study of the superconducting state in the latter alloy. The quantitative estimates of the thermodynamics of PtH at 100 GPa are given for a wide ...
1504.01349v1
2015-04-09
Study of a MA-loaded cavity for compact synchrotron
The untuned magnetic alloy (MA) loaded cavity will be adopted in the recent proposed projects based on compact proton and heavy-ion synchrotron in China. The MA loaded cavity has been operated successfully in many accelerators, but there is no construction and operation experience in China. The small-size MA cores with...
1504.02257v1
2015-04-16
Electron mobility in InxGa1-xN channel HEMTs
In this letter, we report on the theoretical investigations of electron mobility in practically viable designs of InxGa1-xN channel high electron mobility transistors (HEMT). Carriers in such devices are expected to exhibit a higher velocity and hence higher cut-off frequencies (fT) for highly scaled architectures. We ...
1504.04336v1
2015-04-21
Performance Boost in Industrial Multifilamentary Nb3Sn Wires due to Radiation Induced Pinning Centers
We report non-Cu critical current densities of 4.09 * 10^9 A/m^2 at 12 T and 2.27 * 10^9 A/m^2 at 15 T obtained from transport measurements on a Ti-alloyed RRP Nb3Sn wire after irradiation to a fast neutron fluence of 8.9 * 10^21 m^-2. These values are to our knowledge unprecedented in multifilamentary Nb3Sn, and they ...
1504.05366v1
2015-05-10
The progress of neutron texture diffractometer at China Advanced Research Reactor
The first neutron texture diffractometer in China has been built at China Advanced Research Reactor due to the strong demands of texture measurement with neutrons from domestic user community. This neutron texture diffractometer has high neutron intensity, moderate resolution and is mainly applied to study the texture ...
1505.02382v1
2015-05-18
Unique opportunity to harness polarization in GaN to override the conventional power electronics figure-of-merits
Owing to the large breakdown electric field, wide bandgap semiconductors such as SiC, GaN, Ga2O3 and diamond based power devices are the focus for next generation power switching applications. The unipolar trade-off relationship between the area specific-on resistance and breakdown voltage is often employed to compare ...
1505.04651v1
2015-05-21
Non-Contact Measurement of Thermal Diffusivity in Ion-Implanted Nuclear Materials
Knowledge of mechanical and physical property evolution due to irradiation damage is essential for the development of future fission and fusion reactors. Ion-irradiation provides an excellent proxy for studying irradiation damage, allowing high damage doses without sample activation. Limited ion-penetration-depth means...
1505.05902v1
2015-05-21
Grain boundary character distributions in nanocrystalline metals produced by different processing routes
Nanocrystalline materials are defined by their fine grain size, but details of the grain boundary character distribution should also be important. Grain boundary character distributions are reported for ball milled, sputter deposited, and electrodeposited Ni and Ni-based alloys, all with average grain sizes of ~20 nm, ...
1505.05904v2
2015-05-22
Direct Method for Calculating Temperature-Dependent Transport Properties
We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calculated from first princ...
1505.06231v1
2015-06-04
Exploring the feasibility of Fe(Se,Te) conductors by ex-situ Powder-in-Tube method
In this work, the feasibility condition of Powder-In-Tube (PIT) processed wires of Fe(Se,Te) superconductor has been investigated. We faced several technical issues that are extensively described and discussed. In particular, we tested different metals and alloys as external sheaths (Cu, Ag, Nb, Ta, Ni, Fe, cupronickel...
1506.01630v1
2015-06-04
Massively Parallel Phase-Field Simulations for Ternary Eutectic Directional Solidification
Microstructures forming during ternary eutectic directional solidification processes have significant influence on the macroscopic mechanical properties of metal alloys. For a realistic simulation, we use the well established thermodynamically consistent phase-field method and improve it with a new grand potential form...
1506.01684v1
2015-06-08
A Theoretical Examination of Diffusive Molecular Dynamics
Diffusive molecular dynamics is a novel model for materials with atomistic resolution that can reach diffusive time scales. The main ideas of diffusive molecular dynamics are to first minimize an approximate variational Gaussian free energy of the system with respect to the mean atomic coordinates (averaging over many ...
1506.02569v1
2015-06-10
Complex structures in the Au-Cd alloy system: Hume-Rothery mechanism as origin
The binary (simple metal) phase diagram Au-Cd contains a number of intermetallic compounds with various distortions, superlattices and vacancies. To understand the reasons of these structural complexities and their phase stability, we analyze these crystal structures within the nearly free-electron model in the frame o...
1506.03189v1
2015-06-10
The magnetic ground state properties of non-centrosymmetric CePt$_3$B$_{1-x}$Si$_x$
We present a study of the alloying series of the non-centrosymmetric $f$-electron intermetallic CePt$_3$B$_{1-x}$Si$_x$ by means of muon spin rotation and relaxation measurements. In addition, we include a high pressure magnetization investigation of the stoichiometric parent compound CePt$_3$B. From our data we establ...
1506.03419v1
2015-06-19
Direct Measure of Giant Magnetocaloric Entropy Contributions in Ni-Mn-In
Off-stoichiometric alloys based on Ni 2 MnIn have drawn attention due to the coupled first order magnetic and structural transformations, and the large magnetocaloric entropy associated with the transformations. Here we describe calorimetric and magnetic studies of four compositions. The results provide a direct measur...
1506.06168v2
2015-06-23
Coherent Cancellation of Photothermal Noise in GaAs/Al$_{0.92}$Ga$_{0.08}$As Bragg Mirrors
Thermal noise is a limiting factor in many high-precision optical experiments. A search is underway for novel optical materials with reduced thermal noise. One such pair of materials, gallium arsenide and aluminum-alloyed gallium arsenide (collectively referred to as AlGaAs), shows promise for its low Brownian noise wh...
1506.07088v2
2015-06-28
Anomalous Threshold Reduction from <100> Uniaxial Strain for a Low-Threshold Ge Laser
We theoretically investigate the effect of <100> uniaxial strain on a Ge-on-Si laser using deformation potentials. We predict a sudden and dramatic ~200x threshold reduction upon applying sufficient uniaxial tensile strain to the Ge gain medium. This anomalous reduction is accompanied by an abrupt jump in the emission ...
1506.08403v1
2015-06-29
Segregation-induced phase transformations in grain boundaries
Phase transformations in metallic grain boundaries (GBs) present significant fundamental interest in the context of thermodynamics of low-dimensional physical systems. We report on atomistic computer simulations of the Cu-Ag system that provide direct evidence that GB phase transformations in a single-component GB can ...
1506.08882v1
2015-06-30
Nematicity, magnetic fluctuation and ferro-spin-orbital ordering in BaFe$_2$As$_2$ family
Through detailed electronic structure simulations we show that the electronic orbital ordering (between d$_{yz}$ and d$_{xz}$ bands) takes place due to local breaking of in-plane symmetry that generates two non-equivalent $a$, $b$ directions in 122 family of Fe-based superconductors. Orbital ordering is strongly anisot...
1506.08948v2
2015-07-04
Verification of a binary fluid solidification model in the finite-volume flow solver
The aim of this paper is to verify the new numerical implementation of a binary fluid, heat conduction dominated solidification model. First, we extend a semi-analytical solution to the heat diffusion equation, next, the range of its applicability is investigated. It was found that the linearization introduced to the h...
1507.01131v1
2015-07-07
Chemical modification of silicene
Silicene is a two-dimensional material, which is composed of a single layer of silicon atoms with sp2-sp3 mixed hybridization. The sp2-sp3 mixed hybridization renders silicene excellent reactive ability, facilitating the chemical modification of silicene. It has been demonstrated that chemical modification effectively ...
1507.01658v1
2015-07-15
Role of crystal structure and junction morphology on interface thermal conductance
We argue that the relative thermal conductance between interfaces with different morphologies is controlled by crystal structure through $M_{min}/M_c > 1$, the ratio between the {\it minimum mode} count on either side $M_{min}$, and the {\it conserving modes} $M_c$ that preserve phonon momentum transverse to the interf...
1507.04322v1
2015-07-16
Low volume-fraction microstructures in martensites and crystal plasticity
We study microstructure formation in two nonconvex singularly-perturbed variational problems from materials science, one modeling austenite-martensite interfaces in shape-memory alloys, the other one slip structures in the plastic deformation of crystals. For both functionals we determine the scaling of the optimal ene...
1507.04521v1
2015-07-16
Evaluation of the spin diffusion length of AuW alloy by spin absorption experiments in the limit of large spin-orbit interactions
The knowledge of the spin diffusion length $\lambda_{A}$ is a prerequisite for the estimation of the spin Hall angle. We investigate spin current absorption of materials with small $\lambda_{A}$ using AuW stripes inserted in lateral spin-valves. Width variations of the AuW stripe lead to drastic changes of the spin abs...
1507.04567v2
2015-07-16
Strong Linear Dichroism in Spin-Polarized Photoemission from Spin-Orbit-Coupled Surface States
A comprehensive understanding of spin-polarized photoemission is crucial for accessing the electronic structure of spin-orbit coupled materials. Yet, the impact of the final state in the photoemission process on the photoelectron spin has been difficult to assess in these systems. We present experiments for the spin-or...
1507.04664v2
2015-07-18
Addressing the Challenges of Using Ferromagnetic Electrodes in the Molecular Spintronics Devices
Ferromagnetic electrodes chemically bonded with thiol functionalized molecules can produce novel molecular spintronics devices. However, major challenges lie in developing Ferromagnetic electrodes based commercially viable device fabrication scheme that consider the susceptibility of ferromagnetic electrodes to oxidati...
1507.05146v1
2015-07-19
Influence of electric field on the Eu+3 photolumiscence in lead-free ferroelectric Na1/2Bi1/2TiO3
Eu modified Na1/2Bi1/2TiO3 (NBT) was investigated for electric-field induced Eu+3 photoluminescence (PL) and structural changes. Detailed analysis revealed that below a critical Eu composition electric field irreversibly suppresses the structural heterogeneity inherent of the host matrix NBT and brings about a long ran...
1507.05288v1
2015-07-23
Novel thermal effects across first order magnetic transition in Ta doped $HfFe_2$ intermetallic
Novel thermal effects across the first order antiferromagnetic (AFM) - ferromagnetic (FM) transition in an intermetallic alloy are reported. They show instances of warming when heat is extracted from the sample, and cooling when heat is provided to the sample across AFM-FM transition in Ta doped $HfFe_2$, thus providin...
1507.06434v2
2015-07-24
Adding Partial Functions to Constraint Logic Programming with Sets
Partial functions are common abstractions in formal specification notations such as Z, B and Alloy. Conversely, executable programming languages usually provide little or no support for them. In this paper we propose to add partial functions as a primitive feature to a Constraint Logic Programming (CLP) language, namel...
1507.06852v1
2015-07-28
Reproducible domain wall pinning by linear non-topographic features in a ferromagnetic nanowire
We demonstrate that for multilayered magnetic nanowires, where the thickness and composition of the individual layers has been carefully chosen, domain walls can be pinned at non-topographic sites created purely by ion irradiation in a focused ion beam system. The pinning results from irradiation induced alloying leadi...
1507.07847v1
2015-07-31
Lattice vibrations boost demagnetization entropy in shape memory alloy
Magnetocaloric (MC) materials present an avenue for chemical-free, solid state refrigeration through cooling via adiabatic demagnetization. We have used inelastic neutron scattering to measure the lattice dynamics in the MC material Ni45Co5Mn36.6In13.4. Upon heating across the Curie Temperature (TC), the material exhib...
1507.08933v4
2015-08-04
Tailoring superelasticity of soft magnetic materials
Embedding magnetic colloidal particles in an elastic polymer matrix leads to smart soft materials that can reversibly be addressed from outside by external magnetic fields. We discover a pronounced nonlinear superelastic stress-strain behavior of such materials using numerical simulations. This behavior results from a ...
1508.00770v2
2015-06-03
Stable room-temperature ferromagnetic phase at the FeRh(100) surface
Interfaces and low dimensionality are sources of strong modifications of electronic, structural, and magnetic properties of materials. FeRh alloys are an excellent example because of the first-order phase transition taking place at $\sim$400 K from an antiferromagnetic phase at room temperature to a high temperature fe...
1508.01777v1
2015-08-17
Segregation-induced changes in grain boundary cohesion and embrittlement in binary alloys
Grain boundary embrittlement occurs when a solute enriches at a grain boundary and lowers its cohesive energy. While grain boundary enrichment is often attributed to equilibrium segregation effects, most models of embrittlement consider either the energetics of decohesion or the equilibrium adsorption at the boundary, ...
1508.04058v1
2015-08-18
Interface dynamics of a metastable mass-conserving spatially extended diffusion
We study the metastable dynamics of a discretised version of the mass-conserving stochastic Allen-Cahn equation. Consider a periodic one-dimensional lattice with $N$ sites, and attach to each site a real-valued variable, which can be interpreted as a spin, as the concentration of one type of metal in an alloy, or as a ...
1508.04247v1
2015-08-19
New type of stable particle like states in chiral magnets (Chiral bobbers)
We present a new type of a thermodynamically stable magnetic state at interfaces and surfaces of chiral magnets. The state is a soliton solution of micromagnetic equations localized in all three dimensions near a boundary and contains a singularity, but nevertheless has a finite energy. Both features combine to a quasi...
1508.04786v1
2015-08-24
Evidence of field induced inter-ferroelectric transformation as the dominant driving mechanism for anomalous piezoresponse in the morphotropic phase boundary piezoelectric system PbTiO3-BiScO3
The contributory mechanisms associated with high piezoelectric response in piezoelectric ceramics have been examined by in-situ electric field dependent high energy synchro x-ray diffraction study. A comparative study of electric field induced lattice strain and the propensity for non-180o domain switching on two close...
1508.05734v1
2015-08-31
Reconstruction of nuclear quadrupole interaction in (In,Ga)As/GaAs quantum dots observed by transmission electron microscopy
A microscopic study of the individual annealed (In,Ga)As/GaAs quantum dots is done by means of high-resolution transmission electron microscopy. The Cauchy-Green strain-tensor component distribution and the chemical composition of the (In,Ga)As alloy are extracted from the microscopy images. The image processing allows...
1508.07957v1
2015-09-01
First principles thermodynamical modeling of the binodal and spinodal curves in lead chalcogenides
High-throughput ab-initio calculations, cluster expansion techniques and thermodynamic modeling have been synergistically combined to characterize the binodal and the spinodal decompositions features in the pseudo-binary lead chalcogenides PbSe-PbTe, PbS-PbTe, and PbS-PbSe. While our results agree with the available ex...
1509.00502v1
2015-09-05
Surfactant Antimony enhanced Indium incorporation on InGaN (000-1) surface: a DFT study
InGaN is an ideal alloy system for optoelectronic devices due its tunable band gap. Yet high-quality InGaN requires high In concentration, which is a challenging issue that limits its use in green-light LEDs and other devices. In this paper, we investigated the surfactant effect of Sb on the In incorporation on InGaN (...
1509.01689v2
2015-09-11
Change of the charge modulation during superconducting transition in SmFeAsO(0.91)F(0.09) seen by 57Fe Mössbauer spectroscopy
Iron-based superconductor SmFeAsO(0.91)F(0.09) has been investigated by the 57Fe Moessbauer spectroscopy versus temperature with the special attention paid to the region of the superconducting transition at about 47 K. Modulation of the electron charge density was found. It leads to the development of the charge densit...
1509.03451v3
2015-09-14
From soft to hard magnetic Fe-Co-B by spontaneous strain: A combined first principle and thin film study
In order to convert the well-known Fe-Co-B alloy from a soft to a hard magnet, we propose tetragonal strain by interstitial boron. Density functional theory reveals that when B atoms occupy octahedral interstitial sites, the bcc Fe-Co lattice is strained spontaneously. Such highly distorted Fe-Co is predicted to reach ...
1509.04126v1
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
2015-09-21
Induced effects by the substitution of Zn in Cu2ZnSnX4 (X = S and Se)
Based on the density functional theory with hybrid functional approach, we have studied the structural and thermodynamic stabilities of Cu2MSnX4 (M = Zn, Mg, and Ca; X = S and Se) alloy, and have further investigated the electronic and optical properties of stable Cu2MgSnS4 and Cu2MgSnSe4 phases. Thermal stability anal...
1509.06230v2
2015-10-01
CuAlTe$_2$: A promising bulk thermoelectric material
Transport properties of Cu-based chalcopyrite materials are presented using the full potential linear augmented plane wave method and Boltzmann Semi-classical theory. All the studied compounds appear to be direct band gap semiconductors evaluated based on the Tran-Blaha modified Becke-Johnson potential. The heavy and l...
1510.00231v1
2015-10-09
Dynamic reconstruction for atom probe tomography
Progress in the reconstruction for atom probe tomography has been limited since the first implementation of the protocol proposed by Bas et al. in 1995. This approach, and those subsequently developed, assume that the geometric parameters used to build the three-dimensional atom map are constant over the course of an a...
1510.02849v1
2015-10-10
Some aspects of the field evaporation behaviour of GaSb
In-depth analysis of pulsed laser atom probe tomography (APT) data on the field evaporation of the III V semiconductor material GaSb reveals strong variations in charge states, relative abundances of different cluster ions, multiplicity of detector events and spatial correlation of evaporation events, as a function of ...
1510.02909v1
2015-10-10
The CeMIn5 (M = Rh, Ir and Co) System and the Single Energy Scale Model of Metamagnetism
For a decade and a half, CeCoIn$_5$ and related alloys have served as a rich playground to explore the interplay between magnetism and unconventional superconductivity. Despite this extended study, the presence/absence of metamagnetism (MM) in this ternary system remains as an unresolved issue. Here we show that the li...
1510.02991v1
2015-10-15
NEMO5: Achieving High-end Internode Communication for Performance Projection Beyond Moore's Law
Electronic performance predictions of modern nanotransistors require nonequilibrium Green's functions including incoherent scattering on phonons as well as inclusion of random alloy disorder and surface roughness effects. The solution of all these effects is numerically extremely expensive and has to be done on the wor...
1510.04686v1
2015-10-23
In-situ high-pressure Raman scattering studies in PbWO4 up to 48 GPa
The effect of pressure on the Raman spectrum of PbWO4 has been investigated up to 48 GPa in a diamond-anvil cell using neon as pressure-transmitting medium. Changes are detected in the Raman spectrum at 6.8 GPa as a consequence of a structural phase transition from the tetragonal scheelite structure to the monoclinic P...
1510.06842v1
2015-10-26
Spatial evolution of the ferromagnetic phase transition in an exchange graded film
A combination of experiments and numerical modeling was used to study the spatial evolution of the ferromagnetic phase transition in a thin film engineered to have a smooth gradient in exchange strength. Mean-field simulations predict, and experiments confirm that a 100 nm Ni[x]Cu[1-x] alloy film with Ni concentration ...
1510.07535v1
2015-10-30
Efficient implicit integration for finite-strain viscoplasticity with a nested multiplicative split
An efficient and reliable stress computation algorithm is presented, which is based on implicit integration of the local evolution equations of multiplicative finite-strain plasticity/viscoplasticity. The algorithm is illustrated by an example involving a combined nonlinear isotropic/kinematic hardening; numerous backs...
1510.09163v2
2015-10-30
Impact of Extreme Electrical Fields on Charge Density Distributions in Alloys
The purpose of this work is to identify the field evaporation mechanism associated with charge density distribution under extreme fields, linking atom probe tomography (APT) experiments with density functional theory (DFT) modeling. DFT is used to model a materials surface bonding, which affects the evaporation field o...
1510.09220v1
2015-11-01
Reciprocal spin Hall effects in conductors with strong spin-orbit coupling: a review
Spin Hall effect and its inverse provide essential means to convert charge to spin currents and vice versa, which serve as a primary function for spintronic phenomena such as the spin-torque ferromagnetic resonance and the spin Seebeck effect. These effects can oscillate magnetization or detect a thermally generated sp...
1511.00332v1
2015-11-11
Second-Nearest-Neighbor Correlations from Connection of Atomic Packing Motifs in Metallic Glasses and Liquids
Using molecular dynamics simulations, we have studied the atomic correlations characterizing the second peak in the radial distribution function (RDF) of metallic glasses and liquids. The analysis was conducted from the perspective of different connection schemes of atomic packing motifs, based on the number of shared ...
1511.03707v1
2015-11-13
Modeling Disordered Materials with a High Throughput ab-initio Approach
Predicting material properties of disordered systems remains a long-standing and formidable challenge in rational materials design. To address this issue, we introduce an automated software framework capable of modeling partial occupation within disordered materials using a high-throughput (HT) first principles approac...
1511.04373v1
2015-12-04
Cross-plane heat conduction in thin films with ab-initio phonon dispersions and scattering rates
We present a first-principles study of the cross-plane thermal conductivity $\kappa_{\perp}$ in a wide variety of semiconductor thin films. We introduce a simple suppression model that matches variance-reduced Monte Carlo simulations with ab-initio phonon dispersions and scattering rates within $\leq 5\%$ even for anis...
1512.01354v3
2015-12-07
First principles investigation of structural, electronic and optical properties of MgRh intermetallic compound
The structural electronic and optical properties of intermetallic compound MgRh were investigated by using the ab-initio technique from CASTEP code. In this study we have carried out the pseudo-potential plane-wave (PP-PW) method based on the density functional theory (DFT), within the generalized gradient approximatio...
1512.02118v1
2015-12-08
Development of magnetic liquid metal suspensions for magnetohydrodynamics
A new class of materials is developed that is a liquid with both high conductivity and magnetic susceptibility for magnetohydrodynamic (MHD) applications. We develop a general method for making such suspensions and demonstrate that various magnetic and non-magnetic metal particles, from 40 nm - 500 microns in diameter,...
1512.02575v4
2015-12-12
Complex dielectric and impedance behavior of magnetoelectric Fe2TiO5
We have investigated the complex dielectric and impedance properties of magnetoelectric compound Fe2TiO5 (FTO) as a function of temperature (T) and frequency (f) to understand the grain (G) and grain boundary (Gb) contributions to its dielectric response. The temperature and frequency dependent dielectric permittivity ...
1512.03889v1
2015-12-21
Phase diagram and polarization of stable phases of (Ga$_{1-x}$In$_x$)$_2$O$_3$
Using density-functional ab initio calculations, we provide a revised phase diagram of (Ga$_{1-x}$In$_{x})_2$O$_3$. Three phases --monoclinic, hexagonal, cubic bixbyite-- compete for the ground state. In particular, in the $x$$\sim$0.5 region we expect coexistence of hexagonal, $\beta$, and bixbyite (the latter separat...
1512.06570v1
2015-12-22
Deformation concentration for martensitic microstructures in the limit of low volume fraction
We consider a singularly-perturbed nonconvex energy functional which arises in the study of microstructures in shape memory alloys. The scaling law for the minimal energy predicts a transition from a parameter regime in which uniform structures are favored, to a regime in which the formation of fine patterns is expecte...
1512.07023v1
2015-12-24
Theoretical study of the elastic and thermodynamic properties of Pt$_{3}$Al with the L1$_{2}$ structure under high pressure
In this work, the elastic and thermodynamic properties of Pt$_{3}$Al under high pressure are investigated using density functional theory within the generalized gradient approximation. The results of bulk modulus and elastic constants at zero pressure are in good agreement with the available theoretical and experimenta...
1512.07791v1
2016-01-13
Prediction of giant mechanocaloric effects in fluorite-structured superionic materials
Mechanocaloric materials experience a change in temperature when a mechanical stress is adiabatically applied on them. Thus far, only ferroelectrics and superelastic metallic alloys have been considered as potential mechanocaloric compounds to be exploited in solid-state cooling applications. Here we show that giant me...
1601.03376v1
2016-01-14
Intertwined Rashba, Dirac and Weyl Fermions in Hexagonal Hyperferroelectrics
By means of density functional theory based calculations, we study the role of spin-orbit coupling in the new family of ABC hyperferroelectrics [Phys. Rev. Lett. 112, 127601 (2014)]. We unveil an extremely rich physics strongly linked to ferroelectric properties, ranging from the electric control of bulk Rashba effect ...
1601.03643v1
2016-01-22
Numerical simulation of InGaN Schottky solar cell
The Indium Gallium Nitride (InGaN) III-Nitride ternary alloy has the potentiality to allow achieving high efficiency solar cells through the tuning of its band gap by changing the Indium composition. It also counts among its advantages a relatively low effective mass, high carriers\^a mobility, a high absorption coeffi...
1601.05951v1
2016-02-09
The symmetry-adapted configurational ensemble approach to the computer simulation of site-disordered solids
Site-occupancy disorder, defined as the non-periodic occupation of lattice sites in a crystal structure, is a ubiquitous phenomenon in solid-state physics and chemistry. Examples are mineral solid solutions, synthetic non-stoichiometric compounds and metal alloys. The experimental investigation of these materials using...
1602.02937v1
2015-01-13
Towards Security of Additive Layer Manufacturing
Additive Layer Manufacturing (ALM), also broadly known as 3D printing, is a new technology to produce 3D objects. As an opposite approach to the conventional subtractive manufacturing process, 3D objects are created by adding thin material layers over layers. Until recently, they have been used, mainly, for plastic mod...
1602.07536v1
2016-02-25
Point contact tunnelling spectroscopy of the density of states in Tb-Mg-Zn quasicrystals
According to theoretical predictions the quasicrystalline (QC) electronic density of states (DOS) must have a rich and fine spiky structure which actually has resulted elusive. The problem with its absence may be related to poor structural characteristics of the studied specimens, and/or to the non-existence of this sp...
1602.07771v1
2016-02-25
Study of the ultrafast dynamics of ferromagnetic materials with a Quantum Monte Carlo atomistic model
We study of the ultrafast dynamics of the atomic angular momentum in ferrimagnets irradiated by laser pulses. My apply a quantum atomistic spin approach based on the Monte Carlo technique. Our model describes the coherent transfer of angular momentum between the spin and the orbital momentum as well as the quenching of...
1602.07950v1
2016-04-06
High-Tc Superconductivity: Strong Indication of Filamentary-Chaotic Conductance and Possible Routes to Superconductivity Above Room Temperature
The empirical relation of T_co(K)=2740/<q>_c^4 between the transition temperature of optimum doped superconductors T_co and the mean cationic charge <q>_c, a physical paradox, can be recast to strongly support fractal theories of high-T_c superconductors, thereby applying the finding that the optimum hole concentration...
1604.01623v1
2016-04-10
Temperature dependence of elastocaloric effect in natural rubber
The temperature dependence of the elastocaloric (eC) effect in natural rubber (NR) is studied adiabatically and isothermally. A broad temperature span for eC effect from 0 oC to 49 oC is observed. The maximum adiabatic temperature change ({\Delta}T) is 12 K at strain of 6 and occurs at 10 oC. These behaviors can be pre...
1604.02686v2
2016-04-11
Interatomic Fe-H potential for irradiation and embrittlement simulations
The behavior of hydrogen in iron and iron alloys is of interest in many fields of physics and materials science. To enable large-scale molecular dynamics simulations of systems with Fe-H interactions, we develop, based on density-functional theory calculations, an interatomic Fe-H potential in the Tersoff-Brenner forma...
1604.02829v1
2016-04-12
Sustained phase separation and spin glass in Co-doped K$_{x}$Fe$_{2-y}$Se$_{2}$ single crystals
We present Co substitution effects in K$_{x}$Fe$_{2-y-z}$Co$_{z}$Se$_{2}$ (0.06 $\leq$ $z$ $\leq$ 1.73) single crystal alloys. By 3.5\% of Co doping superconductivity is suppressed whereas phase separation of semiconducting K$_{2}$Fe$_{4}$Se$_{5}$ and superconducting/metallic K$_{x}$Fe$_{2}$Se$_{2}$ is still present. W...
1604.03545v1
2016-04-14
Stable artificial solid electrolyte interfaces for lithium batteries
A rechargeable lithium metal battery (LMB), which uses metallic lithium at the anode, is among the most promising technologies for next generation electrochemical energy storage devices due to its high energy density, particularly when Li is paired with energetic conversion cathodes such as sulfur, oxygen/air, and carb...
1604.04200v1
2016-04-19
Fabrication of FeSi and Fe3Si compounds by electron beam induced mixing of [Fe/Si]2 and [Fe3/Si]2 multilayers grown by focused electron beam induced deposition
Fe-Si binary compounds have been fabricated by focused electron beam induced deposition by the alternating use of iron pentacarbonyl, Fe(CO)5, and neopentasilane, Si5H12 as precursor gases. The fabrication procedure consisted in preparing multilayer structures which were treated by low-energy electron irradiation and a...
1604.05536v1
2016-04-19
Insulating and metallic spin glass in K$_{x}$Fe$_{2-δ-y}$Ni$_{y}$Se$_{2}$ (0.06 $\leq$ $y$ $\leq$ 1.44) single crystals
We report electron doping effects by Ni in K$_{x}$Fe$_{2-\delta-y}$Ni$_{y}$Se$_{2}$ (0.06 $\leq$ $y$ $\leq$ 1.44) single crystal alloys. A rich ground state phase diagram is observed. Small amount of Ni ($\sim$ 4\%) suppressed superconductivity below 1.8 K, inducing insulating spin glass magnetic ground state for highe...
1604.05713v1
2016-05-03
Individual electron and hole localization in submonolayer InN quantum sheets embedded in GaN
We investigate sub-monolayer InN quantum sheets embedded in GaN(0001) by temperature-dependent photoluminescence spectroscopy under both continuous-wave and pulsed excitation. Both the peak energy and the linewidth of the emission band associated with the quantum sheets exhibit an anomalous dependence on temperature in...
1605.00865v2
2016-05-05
Superconductivity in multiple phases of compressed GeSb2Te4
Here we report the discovery of superconductivity in multiple phases of the compressed GeSb2Te4 (GST) phase change memory alloy, which has attracted considerable attention for the last decade due to its unusual physical properties with many potential applications. Superconductivity is observed through electrical transp...
1605.01757v1
2016-05-09
Heterogeneous nucleation on a surface with heterogeneous surface energy
In the standard treatment of heterogeneous nucleation on a surface, the energy of the surface is assumed to be homogeneous. Often its value is obtained from some macroscopic measurement. We ask the question what happens if we consider the surface energy to be heterogeneous. This is a straightforward generalization and ...
1605.02670v1