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2014-12-24
Impact of dopant species on the interfacial trap density and mobility in amorphous In-X-Zn-O solution-processed thin-film transistors
Alloying of In/Zn oxides with various X atoms stabilizes the IXZO structures but generates electron traps in the compounds, degrading the electron mobility. To assess whether the latter is linked to the oxygen affinity or the ionic radius, of the X element, several IXZO samples are synthesized by the sol-gel process, w...
1412.7710v1
2015-01-06
Coexistence of Electron-Glass Phase and Persistent Photoconductivity in GeSbTe Compounds
It is demonstrated that persistent-photoconductivity (PPC), well-studied in lightly-doped semiconductors, is observable in GeSbTe compounds using infrared excitation at cryogenic temperatures. The low level of energy-flux necessary to induce an appreciable effect seems surprising given the high carrier-concentration n ...
1501.01163v2
2015-01-13
Weyl semimetal from spontaneous inversion symmetry breaking in pyrochlore oxides
We study the electronic properties of strongly spin-orbit coupled electrons on the elastic pyrochlore lattice. Akin to the Peierls transition in one-dimensional systems, the coupling of the lattice to the electronic degrees of freedom can stabilize a spontaneous deformation of the crystal. This deformation corresponds ...
1501.03029v1
2015-01-21
A Direct Symbolic Execution of SQL Code for Testing of Data-Oriented Applications
Symbolic execution is a technique which enables automatically generating test inputs (and outputs) exercising a set of execution paths within a program to be tested. If the paths cover a sufficient part of the code under test, the test data offer a representative view of the program's actual behaviour, which notably en...
1501.05265v1
2015-01-26
Pairbreaking effect of correlated impurities in a superfluid Fermi liquid
The conventional theory of superconducting alloys does not take into account a discreet character of impurities. Experimental data for superfluid $^3$He in aerogel and for some of high-$T_c$ superconductors reveal a significant discrepancy between the observed temperatures $T_c$ of their transitions in the superfluid o...
1501.06399v1
2015-02-10
Phase Transformations in Binary Colloidal Monolayers
Phase transformations can be difficult to characterize at the microscopic level due to the inability to directly observe individual atomic motions. Model colloidal systems, by contrast, permit the direct observation of individual particle dynamics and of collective rearrangements, which allows for real-space characteri...
1502.02955v1
2015-02-16
Nanoscale Determination of the Mass Enhancement Factor in the Lightly-Doped Bulk Insulator Lead Selenide
Bismuth chalcogenides and lead telluride/selenide alloys exhibit exceptional thermoelectric properties which could be harnessed for power generation and device applications. Since phonons play a significant role in achieving these desired properties, quantifying the interaction between phonons and electrons, which is e...
1502.04694v1
2015-02-23
How to Make Chord Correct
The Chord distributed hash table (DHT) is well-known and frequently used to implement peer-to-peer systems. Chord peers find other peers, and access their data, through a ring-shaped pointer structure in a large identifier space. Despite claims of proven correctness, i.e., eventual reachability, previous work has shown...
1502.06461v2
2015-02-26
Theoretical study of strain-dependent optical absorption in Stranski-Krastanov grown InAs/InGaAs/GaAs/AlGaAs quantum dots
A detailed theoretical study of the optical absorption in self-assembled quantum dots is presented in this paper. A rigorous atomistic strain model as well as a sophisticated electronic band structure model are used to ensure accurate prediction of the optical transitions in these devices . The optimized models present...
1502.07726v1
2015-04-04
Brillouin zone spin filtering mechanism of enhanced TMR and correlation effects in Co(0001)/h-BN/Co(0001) magnetic tunnel junction
The 'Brillouin zone spin filtering' mechanism of enhanced tunneling magnetoresistance (TMR) is described for magnetic tunnel junctions (MTJ) and studied on an example of the MTJ with hcp Co electrodes and hexagonal BN (h-BN) spacer. Our calculations based on local density approximation of density functional theory (LDA...
1504.01017v1
2015-05-01
Premartensite to martensite transition and its implications on the origin of modulation in Ni2MnGa ferromagnetic shape memory alloy
We present here results of temperature dependent high resolution synchrotron x-ray powder diffraction study of sequence of phase transitions in Ni2MnGa. Our results show that the incommensurate martensite phase results from the incommensurate premartensite phase, and not from the austenite phase assumed in the adaptive...
1505.00119v3
2015-05-08
Magnetic spin moment reduction in photoexcited ferromagnets through exchange interaction quenching: Beyond the rigid band approximation
The exchange interaction among electrons is one of the most fundamental quantum mechanical interactions in nature and underlies any magnetic phenomena from ferromagnetic ordering to magnetic storage. The current technology is built upon a thermal or magnetic field, but a frontier is emerging to directly control magneti...
1505.01904v1
2015-05-20
Subcritical excitation of the current-driven Tayler instability by super-rotation
It is known that in a hydrodynamic Taylor-Couette system uniform rotation or a rotation law with positive shear ('super-rotation') are linearly stable. It is also known that a conducting fluid under the presence of a sufficiently strong axial electric-current becomes unstable against nonaxisymmetric disturbances. It is...
1505.05320v2
2015-06-09
Formation and growth of shear bands in glasses: existence of an underlying directed percolation transition
The response of glasses to mechanical loading often leads to the formation of inhomogeneous flow patterns that strongly affect materials properties. Among them, shear bands are ubiquitous in a wide variety of materials, ranging from soft matter systems to metallic alloys. Shear banding is associated with strain localiz...
1506.03049v2
2015-06-21
Site-Specific Contributions to the Band Inversion in a Topological Crystalline Insulator
In a topological crystalline insulator (TCI) the inversion of the bulk valence and conduction bands is a necessary condition to observe surface metallic states. Solid solutions of Pb$_{1-x}$Sn$_x$Te have been shown to be TCI, where band inversion occurs as a result of the band gap evolution upon alloying with Sn. The o...
1506.06328v1
2015-06-24
Monte Carlo simulations of vector pseudospins for strains: Microstructures, and martensitic conversion times
We present systematic temperature-quench Monte Carlo simulations on discrete-strain pseudospin model Hamiltonians to study microstructural evolutions in 2D ferroelastic transitions with two-component vector order parameters ($N_{OP}=2$). The zero value pseudospin is the single high-temperature phase while the low-tempe...
1506.07283v1
2015-06-29
Influence of interphase anisotropy on lamellar eutectic growth patterns
It is well documented in many experiments that crystallographic effects play an important role in the generation of two-phase patterns during the solidification of eutectic alloys. In particular, in lamellar composites, large patches of perfectly aligned lamellae are frequently observed. Moreover, the growth direction ...
1506.08893v1
2015-07-07
Thermal Resonance Fusion
We first show a possible mechanism to create a new type of nuclear fusion, thermal resonance fusion, i.e. low energy nuclear fusion with thermal resonance of light nuclei or atoms, such as deuterium or tritium. The fusion of two light nuclei has to overcome the Coulomb barrier between these two nuclei to reach up to th...
1507.01650v1
2015-07-07
Influence of interstitial Mn on local structure and magnetism in Mn$_{1+δ}$Sb
We report x-ray total scattering and pair distribution function (PDF) studies of the structural relaxation around interstitial manganese (Mn$_i$) in ferromagnetic Mn$_{1+\delta}$Sb ($0.03 \le \delta \le 0.23$) alloys, guided by density functional theory (DFT). Refinements to the experimental PDF using a crystallographi...
1507.01979v2
2015-07-09
Stability of Two-Dimensional Iron-Carbides Suspended across Graphene Pores: First-principles Particle Swarm Optimization
Inspired by recent experimental realizations of two-dimensional (2D) metals and alloys, we theoretically investigate the stability and electronic properties of monolayer (ML) Fe-C compounds and pure Fe. According to our and others theoretical results, the experiment [Science 343, 1228 (2014)] proposed ML pure Fe square...
1507.02418v2
2015-07-09
Structural and mechanical properties of nitrogen-deficient cubic Cr-Mo-N and Cr-W-N systems
The tendency for nitrogen deficiency in cubic Cr-Mo-N and Cr-W-N solid solutions is predicted by a comprehensive evaluation of the lattice spacing, mixing thermodynamics, and elastic properties using first-principles calculations and experimentally confirmed by means of X-ray diffraction. A major conclusion is that the...
1507.02738v1
2015-07-10
Planetary and meteoritic Mg/Si and d30Si variations inherited from solar nebula chemistry
The bulk chemical compositions of planets are uncertain, even for major elements such as Mg and Si. This is due to the fact that the samples available for study all originate from relatively shallow depths. Comparison of the stable isotope compositions of planets and meteorites can help overcome this limitation. Specif...
1507.02922v1
2015-07-14
Ion irradiation effects on a magnetic Si/Ni/Si trilayer and lateral magnetic-nonmagnetic multistrip patterning by focused ion beam
Fabrication of a multistrip magnetic/nonmagnetic structure in a thin sandwiched Ni layer [Si(5 nm)/Ni(10 nm)/Si] by a focused ion beam (FIB) irradiation has been attempted. A control experiment was initially performed by irradiation with a standard 30 keV Ga ion beam at various fluences. Analyses were carried out by Ru...
1507.03748v1
2015-07-20
Thermodynamic theory of equilibrium fluctuations
The postulational basis of classical thermodynamics has been expanded to incorporate equilibrium fluctuations. The main additional elements of the proposed thermodynamic theory are the concept of quasi-equilibrium states, a definition of non-equilibrium entropy, a fundamental equation of state in the entropy representa...
1507.05662v1
2015-07-23
Magneto-transport in closed and open mesoscopic loop structures: A review
Magneto-transport properties in closed and open loop structures are carefully reviewed within a tight-binding formalism. A novel mesoscopic phenomenon where a non-vanishing current is observed in a conducting loop upon the application of an Aharonov-Bohm flux $\phi$ and we explore its behavior in the aspects of quantum...
1507.06420v1
2015-08-05
Giant negative thermal expansion covering room temperature in nanocrystalline GaNxMn3
Materials with negative thermal expansion (NTE), which contract upon heating, are of great interest both technically and fundamentally. Here, we report giant NTE covering room temperature in mechanically milled antiperovksite GaNxMn3 compounds. The micrograin GaNxMn3 exhibits a large volume contraction at the antiferro...
1508.01063v1
2015-09-01
Optical Properties of Mono-Dispersed AlGaN Nanowires in the Single-Prong Growth Mechanism
Growth of mono-dispersed AlGaN nanowires of ternary wurtzite phase is reported using chemical vapour deposition technique in the vapour-liquid-solid process. The role of distribution of Au catalyst nanoparticles on the size and the shape of AlGaN nanowires are discussed. These variations in the morphology of the nanowi...
1509.00193v1
2015-09-18
Band alignment of epitaxial SrTiO3 thin films with (LaAlO3)0.3-(Sr2AlTaO6)0.7 (001)
SrTiO$_{3}$ (STO) epitaxial thin films and heterostructures are of considerable interest due to the wide range of functionalities they exhibit. The alloy perovskite (LaAlO$_{3}$)$_{0.3}$-(Sr$_{2}$AlTaO$_{6}$)$_{0.7}$ (LSAT) is commonly used as a substrate for these material structures due to its structural compatibilit...
1509.05714v1
2015-09-23
Nernst-Ettingshausen effect at the trivial-nontrivial band ordering in topological crystalline insulator Pb1-xSnxSe
The transverse Nernst Ettingshausen (N-E) effect and electron mobility in Pb$_{1-x}$Sn$_x$Se alloys are studied experimentally and theoretically as functions of temperature and chemical composition in the vicinity of vanishing energy gap $E_g$. The study is motivated by the recent discovery that, by lowering the temper...
1509.07052v2
2015-09-24
Design and control of a soft, shape-changing, crawling robot
Soft materials have many important roles in animal locomotion and object manipulation. In robotic applications soft materials can store and release energy, absorb impacts, increase compliance and increase the range of possible shape profiles using minimal actuators. The shape changing ability is also a potential tool t...
1509.07569v1
2015-10-07
Pattern size in Gaussian fields from spinodal decomposition
We study the two-dimensional snake-like pattern that arises in phase separation of alloys described by spinodal decomposition in the Cahn-Hilliard model. These are somewhat universal patterns due to an overlay of eigenfunctions of the Laplacian with a similar wave-number. Similar structures appear in other models like ...
1510.01967v3
2015-10-09
Enhanced and Tunable Spin-Orbit Coupling in Tetragonally Strained Fe-Co-B Films
We have synthesized 20 nm thick films of tetragonally strained interstitial Fe-Co-B alloys epitaxially grown on Au55Cu45 buffer layer. The strained axis is perpendicular to the film plane and the corresponding lattice constant c is enlarged with respect to the in-plane lattice parameter a. By adding the interstitial bo...
1510.02624v1
2015-10-17
Ferrimagnetic nanostructures for magnetic memory bits
Increasing the magnetic data recording density requires reducing the size of the individual memory elements of a recording layer as well as employing magnetic materials with temperature-dependent functionalities. Therefore, it is predicted that the near future of magnetic data storage technology involves a combination ...
1510.05087v1
2015-10-22
Adaptive local basis set for Kohn-Sham density functional theory in a discontinuous Galerkin framework II: Force, vibration, and molecular dynamics calculations
Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn-Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of a...
1510.06489v1
2015-10-25
Incommensurate host-guest structures in compressed elements: Hume-Rothery effects as origin
Discovery of the incommensurate structure in the element Ba under pressure 15 years ago was followed by findings of a series of similar structures in other compressed elements. Incommensurately modulated structures of the host-guest type consist of a tetragonal host structure and a guest structure. The guest structure ...
1510.07242v1
2015-10-28
Robustness of the $0 -π$ transition against compositional and structural ageing in S/F/S heterostructures
We have studied the temperature induced $0 -\pi $ thermodynamic transition in Nb/PdNi/Nb Superconductor/Ferromagnetic/Superconductor (SFS) heterostructures by microwave measurements of the superfluid density. We have observed a shift in the transition temperature with the ageing of the heterostructures, suggesting that...
1510.08265v1
2015-10-30
Suppression of phonon-mediated hot carrier relaxation in type-II InAs/AlAs$_{x}$Sb$_{1-x}$ quantum wells: a practical route to hot carrier solar cells
InAs/AlAs$_{x}$Sb$_{1-x}$ quantum wells are investigated for their potential as hot carrier solar cells. Continuous wave power and temperature dependent photoluminescence indicate a transition in the dominant hot carrier relaxation process from conventional phonon-mediated carrier relaxation below 90 K to a regime wher...
1511.00042v1
2015-11-16
Accurate Measurements of Cross-plane Thermal Conductivity of Thin Films by Dual-Frequency Time-Domain Thermoreflectance (TDTR)
Accurate measurements of the cross-plane thermal conductivity {\Lambda}_cross of a high-thermal-conductivity thin film on a low-thermal-conductivity ({\Lambda}_s) substrate (e.g., {\Lambda}_cross/{\Lambda}_s>20) are challenging, due to the low thermal resistance of the thin film compared to that of the substrate. In pr...
1511.04852v2
2015-11-25
Full Dynamic Control of In-plane Elastic Stress Tensor in Nanomembranes
Strain engineering allows the physical properties of materials and devices to be widely tailored, as paradigmatically demonstrated by strained transistors and semiconductor lasers employed in consumer electronics. For this reason, its potential impact on our society has been compared to that of chemical alloying. Altho...
1511.08192v1
2016-01-08
On the origin of atomistic mechanism of rapid diffusion in alkali halide nanoclusters
To elucidate the atomistic diffusion mechanism responsible for the rapid diffusion in alkali halide nano particles, called Spontaneous Mixing, we execute molecular dynamics simulations with empirical models for KCl-KBr, NaCl-NaBr, RbCl-RbBr and KBr-KI. We successfully reproduce essential features of the rapid diffusion...
1601.01864v1
2016-01-15
Structural Semiconductor-to-Semimetal Phase Transition in Two-Dimensional Materials Induced by Electrostatic Gating
Dynamic control of conductivity and optical properties via atomic structure changes is of tremendous technological importance in information storage. Energy consumption considerations provide a driving force toward employing thin materials in devices. Monolayer transition metal dichalcogenides are nearly atomically-thi...
1601.04073v1
2016-02-05
Configuration Dependence of Band Gap Narrowing and Localization in Dilute GaAs_{1-x} Bi_x Alloys
Anion substitution with bismuth (Bi) in III-V semiconductors is an effective method for experimental engineering of the band gap Eg at low Bi concentrations, in particular in gallium arsenide (GaAs). The inverse Bi-concentration dependence of Eg has been found to be linear at low concentrations x and dominated by a val...
1602.02112v1
2016-02-16
Theoretical study on the anisotropic electronic structure of antiferromagnetic BaFe$_2$As$_2$ and Co-doped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ seen by angle-resolved photoemission
By means of one-step model calculations the strong in-plane anisotropy seen in angle-resolved photoemission of the well-known iron pnictide prototype compounds BaFe$_2$As$_2$ and Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ in their low-temperature antiferromagnetic phases is investigated. The fully-relativistic calculations are bas...
1602.05027v1
2016-02-19
A systematic study of magnetodynamic properties at finite temperatures in doped permalloy from first principles calculations
By means of first principles calculations, we have systematically investigated how the magnetodynamic properties Gilbert damping, magnetization and exchange stiffness are affected when permalloy (Py) (Fe$_{0.19}$Ni$_{0.81}$) is doped with 4d or 5d transition metal impurities. We find that the trends in the Gilbert damp...
1602.06201v2
2016-02-23
Topological Phases in InAs$_{1-x}$Sb$_x$: From Novel Topological Semimetal to Majorana Wire
Superconductor proximitized one-dimensional semiconductor nanowires with strong spin-orbit interaction (SOI) are at this time the most promising candidates for the realization of topological quantum information processing. In current experiments the SOI originates predominantly from extrinsic fields, induced by finite ...
1602.07001v3
2016-02-25
Colossal dielectric constant in high entropy oxides
Entropic contributions to the stability of solids are very well understood and the mixing entropy has been used for forming various solids, for instance such as inverse spinels. A particular development was related to high entropy alloys in which the configurational disorder is responsible for forming simple solid solu...
1602.07842v1
2016-02-26
Two types of all-optical magnetization switching mechanisms using femtosecond laser pulses
Magnetization manipulation in the absence of an external magnetic field is a topic of great interest, since many novel physical phenomena need to be understood and promising new applications can be imagined. Cutting-edge experiments have shown the capability to switch the magnetization of magnetic thin films using ultr...
1602.08525v2
2016-04-08
Melt Flow and Heat Transfer in Laser Drilling
During the laser drilling process the recoil pressure drives melt flow and affects the heat transfer and material removal rate. To get a more realistic picture of the melt flow, a series of differential equations are formulated here that govern the process from pre-heating to melting and evaporation. In particular, the...
1604.02357v1
2016-04-13
Remarkable magnetostructural coupling around the magnetic transition in CeCo$_{0.85}$Fe$_{0.15}$Si
We report a detailed study of the magnetic properties of CeCo$_{0.85}$Fe$_{0.15}$Si under high magnetic fields (up to 16 Tesla) measuring different physical properties such as specific heat, magnetization, electrical resistivity, thermal expansion and magnetostriction. CeCo$_{0.85}$Fe$_{0.15}$Si becomes antiferromagnet...
1604.03985v1
2016-04-18
A Theoretical Investigation of Orientation Relationships and Transformation Strains in Steels
The identification of orientation relationships (ORs) plays a crucial r\^ole in the understanding of solid phase transformations. In steels, the most common models of ORs are the ones by Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS). The defining feature of these and other OR models is the matching of directions a...
1604.05270v2
2016-04-22
Finding and proving the exact ground state of a generalized Ising model by convex optimization and MAX-SAT
Lattice models, also known as generalized Ising models or cluster expansions, are widely used in many areas of science and are routinely applied to alloy thermodynamics, solid-solid phase transitions, magnetic and thermal properties of solids, and fluid mechanics, among others. However, the problem of finding the true ...
1604.06722v1
2016-04-24
Cooling rate dependence of simulated ${\rm Cu_{64.5}Zr_{35.5}}$ metallic glass structure
Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of ${\rm Cu_{64.5}Zr_{35.5}}$ alloy during the cooling in a wide range of cooling rates $\gamma\in(1.5\cdot 10^{9},10^{13})$ K/s. Investigating short- and medium-range order, we show that structure of ${\rm Cu_{64.5}Z...
1604.07024v1
2016-05-11
Influence of structural defects on the magnetocaloric effect in the vicinity of the first order magnetic transition in Fe(50.4)Rh(49.6)
The large magnetocaloric effect (MCE), which accompanies the first order ferromagnetic/anti-ferromagnetic transition in CsCl-ordered Fe-Rh alloys, has been investigated by measurements in slowly cycled magnetic fields of up to 2 T in magnitude for a range of temperatures, 300K < T < 350K. A bulk sample with composition...
1605.03323v1
2016-05-17
Interfacial instability of a planar interface and diffuseness at the solid-liquid interface for pure and binary materials
Topographical and diffuse interface reconfigurations occur with a change in the solidification rate. In this article we pursue the hypothesis that the interface configuration during solidification is determined by the rate of entropy production in the region between a rigorous solid and rigorous liquid phase. We posit ...
1605.05005v2
2016-05-18
Light element diffusion in Mg using first principles calculations: Anisotropy and elastodiffusion
The light elemental solutes B, C, N, and O can penetrate the surface of Mg alloys and diffuse during heat treatment or high temperature application, forming undesirable compounds. We investigate the diffusion of these solutes by determining their stable interstitial sites and the inter-penetrating network formed by the...
1605.05650v2
2016-05-28
Interband characterization and electronic transport control of nanoscaled GeTe/Sb$_2$Te$_3$ superlattices
The extraordinary electronic and optical properties of the crystal-to-amorphous transition in phase-change materials led to important developments in memory applications. A promising outlook is offered by nanoscaling such phase-change structures. Following this research line, we study the interband optical transmission...
1605.08871v1
2016-06-06
Magnetocaloric effect and nature of magnetic transition in low dimensional DyCu2
In this manuscript, we propose a method to prepare small flakes of DyCu2. On top of that we also report on the magnetocaloric effect and nature of magnetic transition of a strongly anisotropic DyCu2 in its low dimension. Magnetization measurements were carried out in the temperature range of 5 to 100 K and up to the ma...
1606.01694v1
2016-06-12
Effect of vacancies on the mechanical properties of zirconium: An ab initio investigation
It is well known that the irradiation-induced defects strongly influence the mechanical properties of zirconium (Zr) or its alloys in nuclear reactors. However, how the point defect changes the mechanical properties has been rarely studied. Here, we systematically investigated the effect of vacancies on the mechanical ...
1606.03700v1
2016-06-26
Spin Filtering through Single-Wall Carbon Nanotubes Functionalized with Single-Stranded DNA
High spin polarization materials or spin filters are key components in spintronics, a niche subfield of electronics where carrier spins play a functional role. Carrier transmission through these materials is "spin selective" i.e. these materials are able to discriminate between "up" and "down" spins. Common spin filter...
1606.07983v1
2016-07-10
Monte-Carlo approach to calculate the ionization of warm dense matter within particle-in-cell simulations
A physical model based on a Monte-Carlo approach is proposed to calculate the ionization dynam- ics of warm dense matters (WDM) within particle-in-cell simulations, and where the impact (col- lision) ionization (CI), electron-ion recombination (RE) and ionization potential depression (IPD) by surrounding plasmas are ta...
1607.02724v2
2016-07-11
Effect of local environment on moment formation in iron silicides
The effect of local environment on the formation of magnetic moments on Fe atoms in iron silicides are studied by combination of ab initio and model calculations. The suggested model includes all Fe d- and Si p-orbitals, intra-atomic Coulomb interactions, inter-atomic Fe-Fe exchange and hopping of electrons to nearest ...
1607.02856v2
2016-07-29
Structural and magnetic properties of Co-N thin films deposited using magnetron sputtering at 523 K
In this work, we studied cobalt nitride (Co-N) thin films deposited using a dc magnetron sputtering method at a substrate temperature (\Ts) of 523\,K. We find that independent of the reactive gas flow (\pn) used during sputtering, the phases of Co-N formed at this temperature seems to be identical having N \pat~$\sim$5...
1607.08701v1
2016-08-12
Unifying interatomic potential, g(r), elasticity, viscosity, and fragility of metallic glasses: analytical model, simulations, and experiments
An analytical framework is proposed to describe the elasticity, viscosity and fragility of metallic glasses in relation to their atomic-level structure and the effective interatomic interaction. The bottom-up approach starts with forming an effective Ashcroft-Born-Mayer interatomic potential based on Boltzmann inversio...
1608.03834v1
2016-08-31
Superelastic stress-strain behavior in ferrogels of different types of magneto-elastic coupling
Colloidal magnetic particles embedded in an elastic polymer matrix constitute a smart material called ferrogel. It responds to an applied external magnetic field by changes in elastic properties, which can be exploited for various applications like dampers, vibration absorbers, or actuators. Under appropriate condition...
1608.08826v1
2016-09-09
Extremely large magnetoresistance in a topological semimetal candidate pyrite PtBi2
While pyrite-type PtBi2 with face-centered cubic structure has been predicted to be a three-dimensional (3D) Dirac semimetal, experimental study on its physical properties remains absent. Here we report the angular-dependent magnetoresistance (MR) measurements of PtBi2 single-crystal under high magnetic fields. We obse...
1609.02626v2
2016-09-09
Effect of lithographically-induced strain relaxation on the magnetic domain configuration in microfabricated epitaxially grown Fe81Ga19
We investigate the role of lithographically-induced strain relaxation in a micron-scaled device fabricated from epitaxial thin films of the magnetostrictive alloy Fe81Ga19. The strain relaxation due to lithographic patterning induces a magnetic anisotropy that competes with the magnetocrystalline and shape induced anis...
1609.02930v2
2016-09-24
First principles modeling of defects in the Al_2O_3/In_0.53Ga_0.47As system
Density functional theory paired with a first order many-body perturbation theory correction is applied to determine formation energies and charge transition energies for point defects in bulk In_0.53Ga_0.47As and for models of the In_0.53Ga_0.47As/Al_2O_3 interface. The results are consistent with previous computation...
1609.07624v1
2016-09-27
A First-Principles Comparative Study of Lithium, Sodium, and Magnesium Storage in Pure and Gallium-Doped Germanium: Competition between Interstitial and Substitutional Sites
Thermodynamics and kinetics of Li, Na, and Mg storage in Ge is studied ab initio. The most stable configurations can consist of tetrahedral, substitutional, or a combination of the two types of sites. In the dilute limit, Li, Na prefer interstitial, while Mg prefers substitutional sites. At higher concentrations of Li,...
1609.08284v1
2016-10-05
Applicability of scaling behavior and power laws in the analysis of the magnetocaloric effect in second-order phase transition materials
In recent years, universal scaling has gained renewed attention in the study of magnetocaloric materials. It has been applied to a wide variety of pure elements and compounds, ranging from rare earth-based materials to transition metal alloys, from bulk crystalline samples to nanoparticles. It is therefore necessary to...
1610.01550v1
2016-10-10
Taming intermittent plasticity at small scales
The extreme miniaturization in modern technology calls for deeper insights into the non-conventional, fluctuation dominated mechanics of materials at micro- to nano-scales. Both experiments and simulations show that sub-micron face-centered-cubic (FCC) crystals exhibit high yield strength, which is, however, compromise...
1610.02897v1
2016-10-11
Characterization and control of ZnGeN2 cation lattice ordering
ZnGeN2 and other heterovalent ternary semiconductors have important potential applications in optoelectronics, but ordering of the cation sublattice, which can affect the band gap, lattice parameters, and phonons, is not yet well understood. Here the effects of growth and processing conditions on the ordering of the Zn...
1610.03512v2
2016-10-12
Monitoring near-surface depth profile of residual stress in weakly anisotropic media by Rayleigh-wave dispersion
Herein we study the inverse problem on inferring depth profile of near-surface residual stress in a weakly anisotropic medium by boundary measurement of Rayleigh-wave dispersion if all other relevant material parameters of the elastic medium are known. Our solution of this inverse problem is based on a recently develop...
1610.06413v2
2016-10-25
Phase decomposition in an Fe-Cr alloy at 402 deg C: Mössbauer spectroscopic study
Phase separation in strained and strain-free samples of Fe84.85Cr15.15 induced by an isothermal annealing at 402 deg C up to 3888 h was studied by means of the Mossbauer spectroscopy. The measured Fe-site spectra were analyzed with two different procedures viz. a hyperfine field distribution and a two-shell superpositi...
1610.08014v1
2016-11-01
Crystallography of deformation twinning in hexagonal close-packed metals. Revisiting the case of the (56 deg, a) contraction twins in magnesium
Contraction twinning in magnesium alloys leads to new grains that are misoriented from the parent grain by a rotation of 56 deg around the a-axis. The classical theory of deformation twinning does not precise the atomic displacements and does not explain why contractions twinning is less frequent than extension twinnin...
1611.00273v1
2016-11-01
Fermi-surface topologies and low-temperature phases of the filled Skutterudite compounds CeOs$_4$Sb$_{12}$ and NdOs$_4$Sb$_{12}$
MHz conductivity, torque magnetometer and magnetization measurements are reported on single crystals of CeOs$_4$Sb$_{12}$ and NdOs$_4$Sb$_{12}$ using temperatures down to 0.5~K and magnetic fields of up to 60~tesla. The field-orientation dependence of the de Haas-van Alphen and Shubnikov-de Haas oscillations is deduced...
1611.00318v1
2016-11-09
A phase space approach to supercooled liquids and a universal collapse of their viscosity
A broad fundamental understanding of the mechanisms underlying the phenomenology of supercooled liquids has remained elusive, despite decades of intense exploration. When supercooled beneath its characteristic melting temperature, a liquid sees a sharp rise in its viscosity over a narrow temperature range, eventually b...
1611.03018v1
2016-11-14
Emerging trends in Topological Insulator and Topological Superconductor
Topological insulators are new class of materials which are characterized by a bulk band gap like ordinary band insulator but have protected conducting states on their edge or surface. These states emerge out due to the combination of spin-orbit coupling and time reversal symmetry. Also these states are insensitive to ...
1611.04252v2
2016-11-14
Nanoscale Chemical Evolution of Silicon Negative Electrodes Characterized by Low-Loss STEM-EELS
Continuous solid electrolyte interface (SEI) formation remains the limiting factor of the lifetime of silicon nanoparticles (SiNPs) based negative electrodes. Methods that could provide clear diagnosis of the electrode degradation are of utmost necessity to streamline further developments. We demonstrate that electron ...
1611.04374v1
2016-11-20
The effect of dynamical compressive and shear strain on magnetic anisotropy in low symmetry ferromagnetic film
Dynamical strain generated upon excitation of a metallic film by a femtosecond laser pulse may become a versatile tool enabling control of magnetic state of thin films and nanostructures via inverse magnetostriction on a picosecond time scale. Here we explore two alternative approaches to manipulate magnetocrystalline ...
1611.06599v3
2017-01-17
Nucleation and growth of hierarchical martensite in epitaxial shape memory films
Shape memory alloys often show a complex hierarchical morphology in the martensitic state. To understand the formation of this twin-within-twins microstructure, we examine epitaxial Ni-Mn-Ga films as a model system. In-situ scanning electron microscopy experiments show beautiful complex twinning patterns with a number ...
1701.04683v1
2017-01-23
Size Effects of Ferroelectric and Magnetoelectric Properties of Semi-ellipsoidal Bismuth Ferrite Nanoparticles
Bismuth ferrite (BiFeO3) is one of the most promising multiferroics with a sufficiently high ferroelectric (FE) and antiferromagnetic transition temperatures, and magnetoelectric (ME) coupling coefficient at room temperature, and thus it is highly sensitive to the impact of cross-influence of applied electric and magne...
1701.06468v1
2017-01-24
Semirelativity in Semiconductors: a Review
Analogy between behavior of electrons in narrow-gap semiconductors (NGS) and relativistic electrons is reviewed. Energy bands in NGS correspond to special relativity, the latter is analogous to two-band k.p description for NGS. Maximum electron velocity in NGS is u=(okolo)1x 10^8 cm/s corresponding to the light velocit...
1701.07067v1
2017-03-08
Oxidation-Mediated Fingering in Liquid Metals
We identify and characterize a new class of fingering instabilities in liquid metals; these instabilities are unexpected due to the large interfacial tension of metals. Electrochemical oxidation lowers the effective interfacial tension of a gallium-based liquid metal alloy to values approaching zero, thereby inducing d...
1703.03011v1
2017-03-15
Budgeted Batch Bayesian Optimization With Unknown Batch Sizes
Parameter settings profoundly impact the performance of machine learning algorithms and laboratory experiments. The classical grid search or trial-error methods are exponentially expensive in large parameter spaces, and Bayesian optimization (BO) offers an elegant alternative for global optimization of black box functi...
1703.04842v2
2017-03-20
Interplay of phase sequence and electronic structure in the modulated martensites of Mn$_2$NiGa from first-principles
We investigate relative stability, structural properties and electronic structure of various modulated martensites of the magnetic shape memory alloy Mn$_{2}$NiGa by means of density functional theory. We observe that the instability in the high-temperature cubic structure first drives the system to a structure where m...
1703.06705v2
2017-03-22
Effects of proton irradiation on flux-pinning properties of underdoped Ba(Fe$_{0.96}$Co$_{0.04}$)$_2$As$_2$ pnictide superconductor
We study the effect of proton irradiation on Ba(Fe$_{0.96}$Co$_{0.04}$)$_2$As$_2$ superconducting single crystals from combined magnetisation and magnetoresistivity measurements. The study allows the extraction of the values of the apparent pinning energy $U_0$ of the samples prior to and after irradiation, as well as ...
1703.07759v1
2017-07-03
Emerging Magnetic Order In Copper Induced By Proximity To Cobalt: A Detailed Soft X-Ray Spectroscopy Study
We present an x-ray magnetic dichroism (XMCD) and soft x-ray absorption spectroscopy (XAS) study to address the nature of emerging magnetic order in metallic Copper as Cobalt is added to the matrix. For this purpose line shape and energy position of XAS and XMCD spectra will be analyzed for a series of Co/Cu alloys as ...
1707.00774v2
2017-07-12
Conduction spectroscopy of a proximity induced superconducting topological insulator
The combination of superconductivity and the helical spin-momentum locking at the surface state of a topological insulator (TI) has been predicted to give rise to p-wave superconductivity and Majorana bound states. The superconductivity can be induced by the proximity effect of a an s-wave superconductor (S) into the T...
1707.03640v1
2017-07-21
Initiation and Propagation of Plastic Yielding in Duplex Stainless Steel
The elastoplastic behavior of a two-phase stainless steel alloy is explored at the crystal scale for five levels of stress biaxiality. The crystal lattice (elastic) strains were measured with neutron diffraction using tubular samples subjected to different combinations of axial load and internal pressure to achieve a r...
1707.06857v1
2017-07-28
A low-background piston-cylinder type hybrid high pressure cell for muon-spin rotation/relaxation experiments
A low background double-wall piston-cylinder-type pressure cell is developed at the Paul Scherrer Institute. The cell is made from BERLYCO-25 (beryllium copper) and MP35N nonmagnetic alloys with the design and dimensions which are specifically adapted to muon-spin rotation/relaxation (muSR) measurements. The mechanical...
1707.09275v2
2017-08-04
Proliferation of Twinning in HCP Metals: Application to Magnesium
Plastic deformation of metallic alloys usually takes place through slip, but occasionally involves twinning. In particular, twinning is important in hexagonal close packed materials where the easy slip systems are insufficient to accommodate arbitrary deformations. While deformation by slip mechanisms is reasonably wel...
1708.01662v1
2017-08-11
Impurity effects on the grain boundary cohesion in copper
Segregated impurities at grain boundaries can dramatically change the mechanical behavior of metals, while the mechanism is still obscure in some cases. Here, we suggest an unified approach to investigate segregation and its effects on the mechanical properties of polycrystalline alloys using the example of 3$sp$ impur...
1708.03597v1
2017-08-14
High-Kinetic Inductance Additive Manufactured Superconducting Microwave Cavity
Investigations into the microwave surface impedance of superconducting resonators have led to the development of single photon counters that rely on kinetic inductance for their operation. While concurrent progress in additive manufacturing, `3D printing', opens up a previously inaccessible design space for waveguide r...
1708.04273v1
2017-08-15
Defect Imaging and Detection of Precipitates Using a New Scanning Positron Microbeam
We report on a newly developed scanning positron microbeam based on threefold moderation of positrons provided by the high intensity positron source NEPOMUC. For brightness enhancement a remoderation unit with a $100\,$nm thin Ni(100) foil and 9.6% efficiency is applied to reduce the area of the beam spot by a factor o...
1708.04424v1
2017-08-16
Fundamental Band Gap and Alignment of Two-Dimensional Semiconductors Explored by Machine Learning
Two-dimensional (2D) semiconductors isoelectronic to phosphorene has been drawing much attention recently due to their promising applications for next-generation (opt)electronics. This family of 2D materials contains more than 400 members, including (a) elemental group-V materials, (b) binary III-VII and IV-VI compound...
1708.04766v1
2017-08-16
Quasiballistic heat removal from small sources studied from first principles
Heat sources whose characteristic dimension $R$ is comparable to phonon mean free paths display thermal resistances that exceed conventional diffusive predictions. This has direct implications to (opto)electronics thermal management and phonon spectroscopy. Theoretical analyses have so far limited themselves to particu...
1708.04906v1
2017-08-29
Ultra-low background mass spectrometry for rare-event searches
Inductively Coupled Plasma Mass Spectrometry (ICP-MS) allows for rapid, high-sensitivity determination of trace impurities, notably the primordial radioisotopes $^{238}$U and $^{232}$Th, in candidate materials for low-background rare-event search experiments. We describe the setup and characterisation of a dedicated lo...
1708.08860v2
2017-09-08
Nuclear Magnetic Relaxation and Knight Shift Due to Orbital Interaction in Dirac Electron Systems
We study the nuclear magnetic relaxation rate and Knight shift in the presence of the orbital and quadrupole interactions for three-dimensional Dirac electron systems (e.g., bismuth-antimony alloys). By using recent results of the dynamic magnetic susceptibility and permittivity, we obtain rigorous results of the relax...
1709.02617v1
2017-09-12
Electric field induced semiconductor-to-metal phase transition in vertical MoTe2 and Mo1-xWxTe2 devices
Over the past years, transition metal dichalcogenides (TMDs) have attracted attention as potential building blocks for various electronic applications due to their atomically thin nature. An exciting development is the recent success in 'engineering' crystal phases of TMD compounds during the growth due to their polymo...
1709.03835v1
2017-09-14
Catalyst design using actively learned machine with non-ab initio input features towards CO2 reduction reactions
In conventional chemisorption model, the d-band center theory (augmented sometimes with the upper edge of d-band for imporved accuarcy) plays a central role in predicting adsorption energies and catalytic activity as a function of d-band center of the solid surfaces, but it requires density functional calculations that...
1709.04576v1