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2006-02-24
Quantum Criticality in doped CePd_1-xRh_x Ferromagnet
CePd_1-xRh_x alloys exhibit a continuous evolution from ferromagnetism (T_C= 6.5 K) at x = 0 to a mixed valence (MV) state at x = 1. We have performed a detailed investigation on the suppression of the ferromagnetic (F) phase in this alloy using dc-(\chi_dc) and ac-susceptibility (\chi_ac), specific heat (C_m), resisti...
0602588v1
2006-07-20
Strained Si, Ge and SiGe alloys modeling with full-zone k.p method optimized from first principle calculation
The electronic energy band structure of strained and unstrained Si, Ge and SiGe alloys is examined in this work using thirty-level k.p analysis. The energy bands are at first obtained with ab initio calculations based on the Local-Density-Approximation of Density-Functional Theory, including a GW correction and relativ...
0607510v2
2006-08-21
Scaling Behaviour and Complexity of the Portevin-Le Chatelier Effect
The plastic deformation of dilute alloys is often accompanied by plastic instabilities due to dynamic strain aging and dislocation interaction. The repeated breakaway of dislocations from and their recapture by solute atoms leads to stress serrations and localized strain in the strain controlled tensile tests, known as...
0608434v1
2006-10-07
Synthesis of nanocrystalline (Co,Ni)Al2O4 spinel powder by mechanical milling of quasicrystalline material
The (Co,Ni)Al2O4 is an aluminum transition metals oxide which falls into the category of aluminate spinels. The synthesis of nano-crystalline spinels has been investigated extensively due to their potential applications such as a high-density magnetic recording, microwave devices magnetic fluids, ceramic pigment as wel...
0610203v1
2007-02-28
Thermo-Mechanical Wave Propagation In Shape Memory Alloy Rod With Phase Transformations
Many new applications of ferroelastic materials require a better understanding of their dynamics that often involve phase transformations. In such cases, an important prerequisite is the understanding of wave propagation caused by pulse-like loadings. In the present study, a mathematical model is developed to analyze t...
0702689v1
2007-02-28
On High Explosive Launching of Projectiles for Shock Physics Experiments
The hydrodynamic operation of the `Forest Flyer' type of explosive launching system for shock physics projectiles was investigated in detail using one- and two-dimensional continuum dynamics simulations. The simulations were insensitive to uncertainties in the material properties, and reproduced measurements of the pro...
0702693v1
2007-03-19
Size effects in the magnetic behaviour of TbAl_2 milled alloys
The study of the magnetic properties depending upon mechanical milling of the ferromagnetic polycrystalline TbAl_2 material is reported. The Rietveld analysis of the X-ray diffraction data reveals a decrease of the grain size down to 14 nm and -0.15 % of variation of the lattice parameter, after 300 hours of milling ti...
0703489v1
1996-02-07
The Structure, Dynamics and Electronic Structure of Liquid Ag-Se Alloys Investigated by Ab Initio Simulation
Ab initio molecular-dynamics simulations have been used to investigate the structure, dynamics and electronic properties of the liquid alloy Ag(1-x)Se(x) at 1350 K and at the three compositions x=0.33, 0.42 and 0.65. The calculations are based on density-functional theory in the local density approximation and on the p...
9602001v1
1999-05-28
Electron Spin Resonance Transistors for Quantum Computing in Silicon-Germanium Heterostructures
We apply the full power of modern electronic band structure engineering and epitaxial heterostructures to design a transistor that can sense and control a single donor electron spin. Spin resonance transistors may form the technological basis for quantum information processing. One and two qubit operations are performe...
9905096v2
2007-09-20
A fast simulator for polycrystalline processes with application to phase change alloys
We present a stochastic simulator for polycrystalline phase-change materials capable of spatio-temporal modelling of complex anneals. This is based on consideration of bulk and surface energies to generate rates of growth and decay of crystallites built up of `monomers' that themselves may be quite complex molecules. W...
0709.3183v2
2008-02-13
Magnetoresistance behavior of a ferromagnetic shape memory alloy: Ni_1.75Mn_1.25Ga
A negative-positive-negative switching behavior of magnetoresistance (MR) with temperature is observed in a ferromagnetic shape memory alloy Ni_1.75Mn_1.25Ga. In the austenitic phase between 300 and 120 K, MR is negative due to s-d scattering. Curiously, below 120K MR is positive, while at still lower temperatures in t...
0802.1801v2
2008-05-15
Evidence of valence band perturbations in GaAsN/GaAs(001): A combined variable-angle spectroscopic ellipsometry and modulated photoreflectance investigation
The contribution of the fundamental gap E_ as well as those of the E_ + Delta(so) and E+ transitions to the dielectric function of GaAs1-xNx alloys near the band edge were determined from variable-angle spectroscopic ellipsometry and modulated photoreflectance spectroscopy analyses. The oscillator strength of the E_ op...
0805.2212v1
2008-06-14
Synthesis of nanocrystalline Spinel phase by Mechanical Milling of Al-Cu-Fe and Al-Cu-Cr-Fe Quasicrystalline alloys
In the present study, low-temperature synthesis of (Cu Fe)Al2O4 and (Cu Cr Fe)Al2O4 spinels from the quasicrystalline phases was investigated with the variation of process parameters during milling and annealing. The milling of the quasicrystalline materials was carried out in an attritor mill at 400 rpm for 40 hours w...
0806.2381v1
2009-01-05
Transport and magnetotransport properties of cold-pressed CrO$_2$ powder, prepared by hydrothermal synthesis
Submicron powder of CrO$_2$ was prepared by hydrothermal synthesis method from chromium trioxide. Particles obtained were of rounded form with mean diameter about 120 nm. The powder (stabilized with thin surface layer of \beta-CrOOH) has been characterized by structural, X-ray and magnetic measurements. The powder (wit...
0901.0491v1
2009-01-11
Optical vibrations of hydrogen in disordered palladium-gold alloys
In the fcc lattice of Pd, hydrogen occupies octahedral interstitial positions with cubic symmetry. One could therefore expect that in dilute solid H solutions in Pd the fundamental band of optical H vibrations should be reduced to a narrow line of 3-fold degenerate, non-interacting isotropic local oscillators. A few at...
0901.1381v1
2009-01-29
Alloying effects on the optical properties of Ge$_{1-x}$Si$_x$ nanocrystals from TDDFT and comparison with effective-medium theory
We present the optical spectra of Ge$_{1-x}$Si$_x$ alloy nanocrystals calculated with time-dependent density-functional theory in the adiabatic local-density ap proximation (TDLDA). The spectra change smoothly as a function of the compositio n $x$. On the Ge side of the composition range, the lowest excitations at the ...
0901.4706v1
2009-07-10
Energy effects on alloying through a re-interpretation of the parameters of Miedema
The parameters Phi and N of Miedema are quoted precise to the second decimal place and are considered very accurate after adjustment in their values to correctly predict the signs of the heats of formation of more than 500 metallic binary systems. In this paper, we argue that Phi is proportional to the electronegativit...
0907.1799v1
2010-02-05
Establishment of Relationships between Material Design and Product Design Domains by Hybrid FEM-ANN Technique
In this paper, research on AI based modeling technique to optimize development of new alloys with necessitated improvements in properties and chemical mixture over existing alloys as per functional requirements of product is done. The current research work novels AI in lieu of predictions to establish association betwe...
1002.1157v1
2010-02-08
Amplitude equations for polycrystalline materials with interaction between composition and stress
We investigate the ability of frame-invariant amplitude equations [G. H. Gunaratne, Q. Ouyang, and H. Swinney, Phys. Rev. E {\bf 50}, 2802 (1994)] to describe quantitatively the evolution of polycrystalline microstructures and we extend this approach to include the interaction between composition and stress. Validation...
1002.1580v1
2010-06-04
Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. Part I: The formation of the $ppσ$-network
Semiconductor glasses exhibit many unique optical and electronic anomalies. We have put forth a semi-phenomenological scenario (J. Chem. Phys. 132, 044508 (2010)) in which several of these anomalies arise from deep midgap electronic states residing on high-strain regions intrinsic to the activated transport above the g...
1006.0771v2
2010-09-02
Short-range order and precipitation in Fe-rich Fe-Cr alloys: Atomistic off-lattice Monte Carlo simulations
Short-range order (SRO) in Fe-rich Fe-Cr alloys is investigated by means of atomistic off-lattice Monte Carlo simulations in the semi-grand canonical ensemble using classical interatomic potentials. The SRO parameter defined by Cowley [Phys. Rev. B 77, 669 (1950)] is used to quantify the degree of ordering. In agreemen...
1009.0511v1
2010-09-05
Search and identification of repeated magnetic compensation in Nd(1-x)R(x)Al(2) (R = Gd, Tb) series
We undertook investigations in polycrystalline R(x)R'(1-x)Al(2) alloys, in particular, explored the stoichiometries, Nd(0.8)Gd(0.2)Al(2) and Nd(0.8)Tb(0.2)Al(2), to study the magnetic compensation behavior in them in the context of contemporary interest. In these admixed rare-earth (RE) intermetallics, the compensation...
1009.0927v1
2010-10-19
Magnetic properties of $σ$-FeCr alloy as calculated with the charge and spin self-consistent KKR(CPA) method
Magnetic properties of a $\sigma-$Fe$_{16}$Cr$_{14}$ alloy calculated with the charge and spin self- consistent Korringa-Kohn-Rostoker (KKR) and combined with coherent potential approximation (KKR-CPA) methods are reported. Non-magnetic state as well as various magnetic orderings were considered, i.e. ferromagnetic (FM...
1010.3856v1
2011-02-24
Polarization-balanced design of AlN/GaN heterostructures: Application to double-barrier structures
Inversion- and depletion-regions generally form at the interfaces between doped leads (cladding layers) and the active region of polar heterostructures like AlN/GaN and other nitride compounds. The band bending in the depletion region sets up a barrier which may seriously impede perpendicular electronic transport. This...
1102.4977v2
2011-04-26
Dealloying of Platinum-Aluminum Thin Films Part I. Dynamics of Pattern Formation
Applying focused ion beam (FIB) nanotomography and Rutherford backscattering spectroscopy (RBS) to dealloyed platinum-aluminum thin films an in-depth analysis of the dominating physical mechanisms of porosity formation during the dealloying process is performed. The dynamical porosity formation due to the dissolution o...
1104.4944v1
2011-06-23
Experimental evidence of Alfvén wave propagation in a Gallium alloy
Experiments with a liquid metal alloy, galinstan, are reported and show clear evidence of Alfv\'en wave propagation as well as resonance of Alfv\'en modes. Galinstan is liquid at room temperature, and although its electrical conductivity is not as large as that of liquid sodium or NaK, it has still been possible to stu...
1106.4727v2
2011-07-12
Amplification of spin-filtering effect by magnetic field in GaAsN alloys
We have found that intensity $I$ and circular polarization degree $\rho$ of the edge photoluminescence, excited in GaAsN alloys by circularly polarized light at room temperature, grow substantially in the longitudinal magnetic field $B$ of the order of 1\,kG. This increase depends on the intensity of pumping and, in th...
1107.2250v1
2011-07-22
Structure of long-period stacking/order Mg-Zn-RE (RE: rare-earth and Y) phases with extended non-stoichiometry ranges
We propose structure models of the unique long-period stacking/order (LPSO) phases formed in the Mg-Zn-RE alloys, based on Z-contrast scanning transmission electron microscopy (STEM) observations and first-principles calculations. The LPSO structures are long-period stacking derivatives of the hcp-Mg structure, and the...
1107.4602v2
2011-09-02
History dependent nucleation and growth of the martensitic phase in a magnetic shape memory alloy Ni$_{45}$Co$_{5}$Mn$_{38}$Sn$_{12}$
We study through the time evolution of magnetization the low temperature (T) dynamics of the metastable coexisting phases created by traversing different paths in magnetic field (H) and T space in a shape memory alloy system, Ni$_{45}$Co$_{5}$Mn$_{38}$Sn$_{12}$. It is shown that these coexisting phases consisting of a ...
1109.0405v2
2011-09-19
Electronic structure and self energies of randomly substituted solids using density functional theory and model calculations
We describe procedures to obtain the electronic structure of disordered systems using either tight binding like models or quite directly from ab inito density functional band structure calculations. The band structure is calculated using super cells much larger than those containing a single minority component atom. We...
1109.4036v1
2011-09-29
Re-examination of the SiGe Raman spectra - Linear chain approximation and ab initio calculations
We propose a (three-dimension) -> (one-dimension) shift of paradigm for basic understanding of Raman spectra of random Si-Ge. Fair contour modeling of Raman spectra is achieved along the linear chain approximation via 1D-cluster version of the phenomenological Percolation scheme, originally developed for zincblende all...
1109.6585v2
2011-11-07
Quadrupolar spectra of nuclear spins in strained InGaAs quantum dots
Self-assembled quantum dots (QDs) are born out of lattice mismatched ingredients where strain plays an indispensable role. Through the electric quadrupolar coupling, strain affects the magnetic environment as seen by the nuclear spins. To guide prospective single-QD nuclear magnetic resonance (NMR) as well as dynamic n...
1111.1499v2
2011-12-22
Theory of band gap bowing of disordered substitutional II-VI and III-V semiconductor alloys
For a wide class of technologically relevant compound III-V and II-VI semiconductor materials AC and BC mixed crystals (alloys) of the type A(x)B(1-x)C can be realized. As the electronic properties like the bulk band gap vary continuously with x, any band gap in between that of the pure AC and BC systems can be obtaine...
1112.5372v2
2012-02-09
Magnetic properties and critical behavior of disordered Fe_{1-x}Ru_x alloys: a Monte Carlo approach
We study the critical behavior of a quenched random-exchange Ising model with competing interactions on a bcc lattice. This model was introduced in the study of the magnetic behavior of Fe_{1-x}Ru_x alloys for ruthenium concentrations x=0%, x=4%, x=6%, and x=8%. Our study is carried out within a Monte Carlo approach, w...
1202.2104v1
2012-03-22
Crystal Chemistry and Magnetic Properties of Manganese Zinc Alloy "YMn2Zn20" Comprising a Mn Pyrochlore Lattice
The chemical composition, crystal structure, and magnetic properties of a manganese zinc alloy with an ideal composition of YMn2Zn20, which comprises a pyrochlore lattice made of Mn atoms, are reported. The compound is stable only when In or Al is partially substituted for Zn. We have determined the actual chemical for...
1203.4887v1
2012-04-18
Controlling bulk conductivity in topological insulators: Key role of anti-site defects
The binary Bi-chalchogenides, Bi2Ch3, are widely regarded as model examples of a recently discovered new form of quantum matter, the three-dimensional topological insulator (TI) [1-4]. These compounds host a single spin-helical surface state which is guaranteed to be metallic due to time reversal symmetry, and should b...
1204.4063v1
2012-05-24
Enhancing magnetocrystalline anisotropy of the Fe70Pd30 magnetic shape memory alloy by adding Cu
Strained epitaxial growth provides the opportunity to understand the dependence of intrinsic and extrinsic properties of functional materials at frozen intermediate stages of a phase transformation. In this study, a combination of thin film experiments and first-principles calculations yields the binding energy and mag...
1205.5422v1
2012-07-15
Synthesis and Characterization of TiFe0.7-xMn0.3Vx (x=0.05, and 0.1) and Ti1-yTayFe0.7Mn0.3 (y=0.2, and 0.4) Nanostructured Metal Hydrides for Low Temperature Applications
Metal hydrides (MH) are often preferred to absorb and desorb hydrogen at ambient temperature and pressure with a high volumetric density. These hydrogen storage alloys create promising prospects for hydrogen storage and can solve the energetic and environmental issues. In the present research work, the goal of our stud...
1207.3503v1
2012-08-28
With no Color and Scent (part III): Architecture of metal shells grown on templates by pulse current electrodeposition
A method of growing mushroom or shell like nanostructured metal convex concave models has been worked out. Silver,copper,nickel,rhodium and Pd-Ni,Pd-Co alloy structures are reproduced as a result of self-assembly of nanowires growing on porous membranes in the course of pulse current electrodeposition. It is shown that...
1208.5546v1
2012-10-11
Growth of carbon nanotubes on quasicrystalline alloys
We report on the synthesis of carbon nanotubes on quasicrystalline alloys. Aligned multiwalled carbon nanotubes (MWNTs) on the conducting faces of decagonal quasicrystals were synthesized using floating catalyst chemical vapor deposition. The alignment of the nanotubes was found perpendicular to the decagonal faces of ...
1210.3108v1
2012-10-26
Enhancement of superconductivity by external magnetic field in magnetic alloys
An asymptotic solution of the thermodynamics of a BCS superconductor containing spin 1/2 and 7/2 magnetic impurities, obtained recently in Ref. 1 is exploited to derive the expressions for critical magnetic field $H_{\mathrm{c}}(T)$ . The credibility of the resulting theoretical equations, which depend on the magnetic ...
1210.7104v1
2013-01-18
Engineering quantum anomalous Hall phases with orbital and spin degrees of freedom
Combining tight-binding models and first principles calculations, we investigate the quantum anomalous Hall (QAH) effect induced by intrinsic spin-orbit coupling (SOC) in buckled honeycomb lattice with sp orbitals in an external exchange field. Detailed analysis reveals that nontrivial topological properties can arise ...
1301.4426v1
2013-02-08
In situ visualization of Ni-Nb bulk metallic glasses phase transition
We report the results of the Ni-based bulk metallic glass structural evolution and crystallization behavior in situ investigation. The X-ray diffraction (XRD), transmission electron microscopy (TEM), nano-beam diffraction (NBD), differential scanning calorimetry (DSC), radial distribution function (RDF) and scanning pr...
1302.1982v2
2013-02-14
Evidence for length-dependent wire expansion, filament dedensification and consequent degradation of critical current density in Ag-alloy sheathed Bi-2212 wires
It is well known that longer Bi-2212 conductors have significantly lower critical current density (Jc) than shorter ones, and recently it has become clear that a major cause of this reduction is internal gas pressure generated during heat treatment, which expands the wire diameter and dedensifies the Bi-2212 filaments....
1302.3370v1
2013-03-12
Démixtion et ségrégation superficielle dans les alliages fer-chrome
Ferritic steels possibly strengthened by oxide dispersion are candidates as structural materials for generation IV and fusion nuclear reactors. Their use is limited by incomplete knowledge of the iron-chromium phase diagram at low temperatures and of the phenomena inducing preferential segregation of one element at gra...
1303.2938v1
2013-03-20
Performance of Titanium-Oxide/Polymer Insulation in Bi-2212/Ag-alloy Round Wire Wound Superconducting Coils
Conductor insulation is one of the key components needed to make Ag-alloy clad Bi2Sr2CaCu2O8+x (Bi-2212/Ag) superconducting round wire (RW) successful for high field magnet applications as dielectric standoff and high winding current densities (Jw) directly depend on it. In this study, a TiO2/polymer insulation coating...
1303.4810v1
2013-03-20
Genetic Design of Enhanced Valley Splitting towards a Spin Qubit in Silicon
Electronic spins in Silicon (Si) are rising contenders for qubits -- the logical unit of quantum computation-- owing to its outstanding spin coherence properties and compatibility to standard electronics. A remarkable limitation for spin quantum computing in Si hosts is the orbital degeneracy of this material's conduct...
1303.4932v1
2013-04-30
SiGe Raman spectra vs. local clustering/anticlustering : Percolation scheme and ab initio calculations
We formalize within the percolation scheme, that operates along the linear chain approximation, namely at one dimension (1D), an intrinsic ability behind Raman scattering to achieve a quantitative insight into local clustering or anticlustering in an alloy, using SiGe as a case study. For doing so, we derive general ex...
1304.7970v1
2013-05-22
Interface kinetics in phase field models: isothermal transformations in binary alloys and steps dynamics in molecular-beam-epitaxy
We present a unified description of interface kinetic effects in phase field models for isothermal transformations in binary alloys and steps dynamics in molecular-beam-epitaxy. The phase field equations of motion incorporate a kinetic cross-coupling between the phase field and the concentration field. This cross coupl...
1305.5052v2
2013-07-08
5d transition metal oxide IrO2 as a material for spin current detection
Devices based on a pure spin current (a flow of spin angular momentum) have been attracting increasing attention as key ingredients for low-dissipation electronics. To integrate such spintronics devices into charge-based technologies, an electric detection of spin current is essential. Inverse spin Hall effect converts...
1307.2121v1
2013-07-11
On chemical order and interfacial segregation in $γ^\prime$ (AlAg$_2$) precipitates
A detailed study has been carried out on $\gamma^\prime$ (AlAg$_2$) precipitates in Al-Ag and Al-Ag-Cu alloys to reconcile the conflicting reports on chemical ordering and stacking faults in this phase. High angle annular dark field scanning transmission electron microscopy and convergent beam electron diffraction show...
1307.2996v3
2013-07-16
Influence of the Core/Shell Interface on Biexciton Auger Recombination in Individual Nanocrystal Quantum Dots
Previous single-particle spectroscopic studies of colloidal quantum dots have indicated a significant spread in biexciton lifetimes across an ensemble of nominally identical nanocrystals. It has been speculated that in addition to dot-to-dot variation in physical dimensions, this spread is contributed to by variations ...
1307.4433v3
2013-08-18
Simulation of the nanostructure evolution under irradiation in Fe-C alloys
Neutron irradiation induces in steels nanostructural changes, which are at the origin of the mechanical degradation that these materials experience during operation in nuclear power plants. Some of these effects can be studied by using as model alloy the iron-carbon system. The Object Kinetic Monte Carlo technique ha...
1308.3866v1
2013-09-27
Preparation and tunable mid-IR optical properties of ternary Cd_{1-x}Pb_xS nanocrystals by mechanical alloying
Composition-tunable ternary Cd1-xPbxS nanocrystals (NCs) are very important materials for remote sensing and detecting in the infrared (IR) wavelength region. They are, however, almost exclusively prepared by wet chemical routes which leads to surface-capped nanoparticles. The surface capping molecules could move their...
1309.7148v2
2013-10-23
Magnetic properties and electronic structure of Mn-Ni-Ga magnetic shape memory alloys
Influence of disorder, antisite defects, martensite transition and compositional variation on the magnetic properties and electronic structure of Mn$_2$NiGa and Mn$_{1+x}$Ni$_{2-x}$Ga magnetic shape memory alloys have been studied by using full potential spin-polarized scalar relativistic Korringa-Kohn-Rostocker (FP-SP...
1310.6130v2
2013-11-25
Structural and Dielectric Characterization on Multiferroic xNi0.9Zn0.1Fe2O4/(1-x)PbZr0.52Ti0.48O3 Particulate Composite
We have carried out the powder x-ray diffraction and dielectric studies on multiferroic particulate composite xNi0.9Zn0.1Fe2O4/(1-x)PbZr0.52Ti0.48O3 with x=0.15, 0.30, 0.45, 0.60, 0.75 and 0.90 to explore the structural and ferroelectric properties. A conventional double sintering method was used to prepare the xNi0.9Z...
1311.6217v2
2013-12-11
Structural and electronic properties of the mu-phase Fe-Mo compounds
Structural (lattice parameters and sublattice occupancies) and electronic (charge-density and electric field gradient) properties in a series of compounds mu-Fe_(100-x)Mo_x were studied experimentally (X-ray diffraction and Mossbauer spectroscopy) and theoretically (charge and spin self-consistent KorringaKohnRostoker ...
1312.3130v2
2014-03-07
Analysis of Femoral Components of Cemented Total Hip- Arthroplasty
In cemented Total Hip Arthroplasty (THA), material chosen for femoral stem and cross section of stem itself, proved to be critical parameters for, stress distribution in the femoral components, interfacial stresses and micro movements. Titanium alloy (Ti6Al4V), when used as a material for femoral stem, recorded large d...
1403.1867v1
2014-03-22
Effect of Aspect Ratio and Boundary Conditions in Modeling Shape Memory Alloy Nanostructures with 3D Coupled Dynamic Phase-Field Models
The behavior of shape memory alloy (SMA) nanostructures is influenced by strain rate and temperature evolution during dynamic loading. The coupling between temperature, strain and strain rate effects is essential to capture inherent thermo-mechanical behavior in SMAs. In this paper, we propose a new fully coupled therm...
1403.5608v2
2014-07-11
Effects of dilute substitutional solutes on carbon in $α$-Fe: interactions and associated carbon diffusion from first-principles calculations
By means of first-principles calculations coupled with the kinetic Monte Carlo simulations, we have systematically investigated the effects of dilute substitutional solutes on the behaviors of carbon in $\alpha$-Fe. Our results uncover that: ($i$) Without the Fe vacancy the interactions between most solutes and carbon ...
1407.2993v1
2014-07-14
An Alloy Verification Model for Consensus-Based Auction Protocols
Max Consensus-based Auction (MCA) protocols are an elegant approach to establish conflict-free distributed allocations in a wide range of network utility maximization problems. A set of agents independently bid on a set of items, and exchange their bids with their first hop-neighbors for a distributed (max-consensus) w...
1407.5074v2
2014-07-27
The nanostructure evolution in Fe-C systems under irradiation at 560 K
This work extends our Object Kinetic Monte Carlo model for neutron irradiation-induced nanostructure evolution in Fe-C alloys to consider higher irradiation temperatures. The previous study concentrated on irradiation temperatures < 370 K. Here we study the evolution of vacancy and self-interstitial atom (SIA) cluster ...
1407.7215v1
2014-07-30
Electronic structure, metamagnetism and thermopower of LaSiFe$_{12}$ and interstitially doped LaSiFe$_{12}$
We present a systematic investigation of the effect of H, B, C, and N interstitials on the electronic, lattice and magnetic properties of La(Fe,Si)$_{13}$ using density functional theory. The parent LaSiFe$_{12}$ alloy has a shallow, double-well free energy function that is the basis of itinerant metamagnetism. On incr...
1407.7975v2
2014-08-02
Nuclear magnetic resonance inverse spectra of InGaAs quantum dots: Atomistic level structural information
A wealth of atomistic information is contained within a self-assembled quantum dot (QD), associated with its chemical composition and the growth history. In the presence of quadrupolar nuclei, as in InGaAs QDs, much of this is inherited to nuclear spins via the coupling between the strain within the polar lattice and t...
1408.0373v2
2014-09-03
Nanoscale confinement of all-optical switching in TbFeCo using plasmonic antennas
All-optical switching (AOS) of magnetic domains by femtosecond laser pulses was first observed in the transition metal-rare earth (TM-RE) alloy GdFeCo1-5; this phenomenon demonstrated the potential for optical control of magnetism for the development of ever faster future magnetic recording technologies. The technologi...
1409.1280v1
2014-09-05
Monoclinic (Mc) phase and electric field induced phase transformation in BaTiO3
For decades it has been a well-known fact that among the few ferroelectric compounds in the perovskite family namely BaTiO3, KNbO3, PbTiO3 Na1/2Bi1/2TiO3 the dielectric and piezoelectric properties of BaTiO3 is considerably higher than the others in polycrystalline form at room temperature. Further, similar to ferroele...
1409.1692v1
2014-09-30
Investigation of the anisotropic electron g factor as a probe of the electronic structure of GaBi$_{x}$As$_{1-x}$/GaAs epilayers
The electron Land\'e g factor ($g^{*}$) is investigated both experimentally and theoretically in a series of GaBi$_{x}$As$_{1-x}$/GaAs strained epitaxial layers, for bismuth compositions up to $x = 3.8$%. We measure $g^{*}$ via time-resolved photoluminescence spectroscopy, which we use to analyze the spin quantum beats...
1409.8467v1
2014-10-02
Electronic correlations in Fe at Earth's inner core conditions: effect of doping with Ni
We have studied the body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed (hcp) phases of Fe alloyed with 25 at. % of Ni at Earth's core conditions using an ab initio local density approximation + dynamical mean-field theory (LDA+DMFT) approach. The alloys have been modeled by ordered crystal ...
1410.0596v1
2014-11-03
Synthesis from Formal Partial Abstractions
Developing complex software systems is costly, time-consuming and error-prone. Model- driven development (MDD) promises to improve software productivity, timeliness, quality and cost through the transformation of abstract application models to code-level implementations. However, it remains unreasonably difficult to bu...
1411.0481v1
2014-11-06
Thermally induced changes of structure in Ni$_{50}$Mn$_{25+x}$Ga$_{25-x}$ magnetic shape memory single crystals with very low twinning stress
In search for the origins of the extraordinary low twinning stress of Ni-Mn-Ga magnetic shape memory alloys we studied the thermally induced changes of structure in Ni$_{50}$Mn$_{25+x}$Ga$_{25-x}$ ($x$=2.7--3.9) single crystal samples and compared them with twinning stress dependences. The alloys exhibited transformati...
1411.1550v1
2014-11-19
Internally Oxidized Nb3Sn Strands with Fine Grain Size and High Critical Current Density
Nb3Sn superconducting strands are the most practical conductors to generate high magnetic fields (12-16 T), and thus have significant applications in nuclear magnetic resonance (NMR), and great potential for fusion reactors and particle accelerator magnets. High critical current density (Jc) is a key parameter for such...
1411.5397v1
2014-12-11
Characterization of precipitation in Al-Li alloy AA2195 by means of atom probe tomography and transmission electron microscopy
The microstructure of the commercial alloy AA2195 was investigated on the nano-scale after conducting a T8 tempering. This particular thermo-mechanical treatment of the specimen resulted in the formation of platelet-shaped $T_{1}$ ($Al_{2}CuLi$)/ $\theta^{'}$($Al_{2}Cu$) within the Al-matrix. The electrochemically prep...
1412.3727v1
2014-12-24
Probing the magnetic phases in the Ni-V alloy close to the disordered ferromagnetic quantum critical point with muSR
Zero (ZF) and longitudinal field (LF) muon spin relaxation data of the {\it d}-metal alloy Ni$_{1-x}$V$_{x}$ are presented at several vanadium concentrations $x$ below and above the critical $x_c \approx 11$% where long-range ferromagnetic (FM) order is suppressed. The clear single precession frequency observed for Ni,...
1412.7671v1
2015-01-30
Unconventional phase selection in high-driven systems: A complex metastable structure prevails over simple stable phases
Phase selection in deeply undercooled liquids and devitrified glasses during heating involves complex interplay between the barriers to nucleation and the ability for these nuclei to grow. During the devitrification of glassy alloys, complicated metastable structures often precipitate instead of simpler, more stable co...
1502.00023v1
2015-04-30
Visualization of steps and surface reconstructions in Helium Ion Microscopy with atomic precision
Helium Ion Microscopy is known for its surface sensitivity and high lateral resolution. Here, we present results of a Helium Ion Microscopy based investigation of a surface confined alloy of Ag on Pt(111). Based on a change of the work function of 25\,meV across the atomically flat terraces we can distinguish Pt rich f...
1505.00020v3
2015-08-19
Phason space analysis and structure modeling of 100 A-scale dodecagonal quasicrystal in Mn-based alloy
The dodecagonal quasicrystal classified into the five-dimensional space group P126/mmc, recently discovered in a Mn-Cr-Ni-Si alloy, has been analyzed using atomic-resolution spherical aberration-corrected electron microscopy, i.e. high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and ...
1508.04563v1
2015-09-15
Formation of hexagonal Boron Nitride on Graphene-covered Copper Surfaces
Graphene-covered copper surfaces have been exposed to borazine, (BH)3(NH)3, with the resulting surfaces characterized by low-energy electron microscopy. Although the intent of the experiment was to form hexagonal boron nitride (h-BN) on top of the graphene, such layers were not obtained. Rather, in isolated surface are...
1509.04531v2
2015-09-28
Thermoelectric properties of rare earth filled type-I like Clathrate, Dy8Al16Si30
Type-I clathrates with a cage structure are known to be of importance for thermoelectric applications as the cage can be filled with a guest atom which leads to reduced thermal conductivity. Among the type-I clathrates, Si-based alloys are of relevance for high temperature application and most importantly because they ...
1509.08277v1
2015-10-09
Magnetic anisotropy of polycrystalline high-temperature ferromagnetic Mn$_x$Si$_{1-x}$ ($x\approx0.5$) alloy films
A set of thin film Mn$_x$Si$_{1-x}$ alloy samples with different manganese concentration x = 0.44 - 0.63 grown by the pulsed laser deposition (PLD) method onto the Al$_2$O$_3$(0001) substrate was investigated in the temperature range 4 - 300 K using ferromagnetic resonance (FMR) measurements in the wide range of freque...
1510.02634v1
2015-10-30
Structural-disorder and its effect on the mechanical properties in single-phase TaNbHfZr high-entropy alloys
Equiatomic TaNbHfZr refractory high-entropy alloys (HEAs) were synthesized by arc-melting. The HEAs were annealed at 1800{\deg}C for different times, at maximum up to 8 days. Their on average body-centered cubic (bcc), solid-solution structure was confirmed by X-ray (XRD) and neutron (ND) diffraction, respectively. The...
1510.09047v1
2015-12-06
Bayesian inference and model comparison for metallic fatigue data
In this work, we present a statistical treatment of stress-life (S-N) data drawn from a collection of records of fatigue experiments that were performed on 75S-T6 aluminum alloys. Our main objective is to predict the fatigue life of materials by providing a systematic approach to model calibration, model selection and ...
1512.01779v1
2015-12-11
Ultra-low magnetic damping of a metallic ferromagnet
The phenomenology of magnetic damping is of critical importance for devices that seek to exploit the electronic spin degree of freedom since damping strongly affects the energy required and speed at which a device can operate. However, theory has struggled to quantitatively predict the damping, even in common ferromagn...
1512.03610v1
2016-01-22
Phase stability, local chemical disorder and its effect on the mechanical properties of refractory high-entropy alloys
Equiatomic TaNbHfZr and TaNbHfZrTi high-entropy alloys (HEAs) have been investigated for their phase stability, short-range clustering (SRC) type chemical ordering, other structural phenomena and and the effects on strengthening. Ab-initio calculations have been done to determine the thermodynamic stability parameters....
1601.06015v1
2016-04-02
Manufacturing of Aluminum Composite Material Using Stir Casting Process
Manufacturing of aluminum alloy based casting composite materials via stir casting is one of the prominent and economical route for development and processing of metal matrix composites materials. Properties of these materials depend upon many processing parameters and selection of matrix and reinforcements. Literature...
1604.01251v1
2016-04-11
A fully relativistic description of spin-orbit torques by means of linear response theory
Symmetry and magnitude of spin-orbit torques (SOT), i.e., current-induced torques on the magnetization of systems lacking inversion symmetry, are investigated in a fully relativistic linear response framework based on the Kubo formalism. By applying all space-time symmetry operations contained in the magnetic point gro...
1604.02798v1
2016-04-26
Unconventional superconductivity in low density electron systems and conventional superconductivity in hydrogen metallic alloys under pressure
In a short review-article we first discuss the results, which are mainly devoted to the generalizations of the famous Kohn-Luttinger mechanism of superconductivity in purely repulsive fermion systems at low electron densities. In the context of repulsive-U Hubbard model and Shubin-Vonsovsky model we consider briefly th...
1604.07583v2
2016-05-11
Faceted interfaces: a key feature to quantitative understanding of transformation morphology
Faceted interfaces are a key feature in self-resembling morphologies of many microstructures generated from solid state phase transformations. Interpretations, predictions and simulations of the faceted morphologies remain a challenge, especially for systems in which irrational orientation relationships (ORs) between t...
1605.03249v2
2016-05-23
Electronic Structure of FeAl Alloy Studied by Resonant Photoemission Spectroscopy and Ab Initio Calculations
Resonant photoemission spectroscopy has been used to investigate the character of Fe 3d states in FeAl alloy. Fe 3d states have two different character, first is of itinerant nature located very close to the Fermi level, and second, is of less itinerant (relatively localized character), located beyond 2 eV below the Fe...
1605.06967v1
2016-06-03
Spectral descriptors for bulk metallic glasses based on the thermodynamics of competing crystalline phases
Metallic glasses have attracted considerable interest in recent years due to their unique combination of superb properties and processability. Predicting bulk metallic glass formers from known parameters remains a challenge and the search for new systems is still performed by trial and error. It has been speculated tha...
1606.01162v2
2016-06-08
Role of Hydrogen in the Electronic Properties of CaFeAsH-based Superconductors
The electronic and magnetic properties of the new hydride superconductor CaFeAsH, which superconducts up to 47 K when electron-doped with La, and the isovalent alloy system CaFeAsH$_{1-x}$F$_x$ are investigated using density functional based methods. The $\vec Q = (\pi,\pi,0)$ peak of the nesting function $\xi(\vec q)$...
1606.02432v1
2016-08-19
Self-optimizing layered hydrogen evolution catalyst with high basal-plane activity
Hydrogen is a promising energy carrier and key agent for many industrial chemical processes1. One method for generating hydrogen sustainably is via the hydrogen evolution reaction (HER), in which electrochemical reduction of protons is mediated by an appropriate catalyst-traditionally, an expensive platinum-group metal...
1608.05755v1
2016-09-02
Influence of Cu deposition potential on the giant magnetoresistance and surface roughness of electrodeposited Ni-Co/Cu multilayers
It has been shown previously for electrodeposited Co/Cu multilayers that the single-bath electrodeposition process can be optimized from an electrochemical point of view in order to avoid unwanted Co dissolution and incorporation of Co in the non-magnetic layer during the Cu deposition pulse. In the present work, elect...
1609.00597v1
2016-09-06
Quasiperiodic Frank-Kasper phases derived from the square-triangle dodecagonal tiling
Frank-Kasper (F-K) phases form an important set of large-cell crystalline structures describing many inter-metallic alloys. They are usually described in term of their atomic environments, with atoms having $12, 14, 15$ and $16$ neighbours, coded into the canonical $Z_p$ cells (with $p$ the coordination number), the ca...
1609.01624v1
2016-09-17
Enhanced visible light absorption in ZnO/GaN heterostructured nanofilms
ZnO/GaN alloys exhibit exceptional photocatalyst applications owing to the flexibly tunable band gaps that cover a wide range of the solar spectrum, and thus have attracted extensive attentions over the past few years. In this study, first-principles calculations were employed to investigate structural stabilities and ...
1609.05340v2
2016-10-05
Electric field gradients in Zr$_8$Ni$_{21}$ and Hf$_8$Ni$_{21}$ intermetallic compounds; Results from perturbed angular correlation measurements and first-principles density functional theory
Numerous technological applications of Ni-based Zr and Hf intermetallic alloys promoted comprehensive studies in Zr$_8$Ni$_{21}$ and Hf$_8$Ni$_{21}$ by perturbed angular correlation (PAC) spectroscopy, which were not studied earlier until this report. The different phases produced in the samples have been identified by...
1610.01414v3
2016-10-26
Influences of Granular Constraints and Surface Effects on the Heterogeneity of Elastic, Superelastic, and Plastic Responses of Polycrystalline Shape Memory Alloys
Deformation heterogeneities within microstructures of polycrystalline shape memory alloys (SMAs) during superelastic stressing are studied using both experiments and simulations. In situ X-ray diffraction, specifically the far-field high energy diffraction microscopy (ff-HEDM) technique was used to non-destructively me...
1610.08429v3
2016-11-09
Understanding and reducing deleterious defects in metastable alloy GaAsBi
Technological applications of novel metastable materials are frequently inhibited by abundant defects residing in these materials. Using first-principles methods we investigate the point defect thermodynamics and phase segregation in the technologically-important metastable alloy GaAsBi. Our calculations predict defect...
1611.03031v1
2016-11-10
Magnetism and ultra-fast magnetization dynamics of Co and CoMn alloys at finite temperature
Temperature-dependent magnetic experiments like pump-probe measurements generated by a pulsed laser have become a crucial technique for switching the magnetization in the picosecond time scale. Apart from having practical implications on the magnetic storage technology, the research field of ultrafast magnetization pos...
1611.03541v2
2017-01-11
The Robustness of Cluster Expansion: Assessing the Roles of Relaxation and Numerical Error
Cluster expansion (CE) is effective in modeling the stability of metallic alloys, but sometimes cluster expansions fail. Failures are often attributed to atomic relaxation in the DFT-calculated data, but there is no metric for quantifying the degree of relaxation. Additionally, numerical errors can also be responsible ...
1701.03080v1
2017-01-19
Dynamics and control of gold-encapped gallium arsenide nanowires imaged by 4D electron microscopy
Eutectic related reaction is a special chemical/physical reaction involving multiple phases, solid and liquid. Visualization of phase reaction of composite nanomaterials with high spatial and temporal resolution provides a key understanding of alloy growth with important industrial applications. However, it has been a ...
1701.05310v2