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2006-03-08 | Curie temperature control by band parameters tuning in Pb(1-x-y-z)Mn(x)Sn(y)Eu(z)Te | We present the study of magnetic and transport properties of
Pb(1-x-y-z)Mn(x)Sn(y)Eu(z)Te. AC magnetic susceptibility measurements as well
as transport characterization were performed. The obtained results indicate
that the presence of two types of magnetic ions influences magnetic properties
of investigated IV-VI semi... | 0603196v1 |
2006-03-10 | Prediction of new crystal structure phases in metal borides: a lithium monoboride analog to MgB2 | Modern compound prediction methods can efficiently screen large numbers of
crystal structure phases and direct the experimental search for new materials.
One of the most challenging problems in alloy theory is the identification of
stable phases with a never seen prototype; such predictions do not always
follow rationa... | 0603304v2 |
2006-03-21 | The Influence of Synthesis Parameters on Microstructures and Superconducting Properties of MgB2 Bulks | We succeeded in the synthesis of high-Jc MgB2 bulks via high energy
ball-milling of elemental Mg and B powder at ambient temperatures.
Alternatively to longtime mechanical alloying technique, the mixed powder was
ball-milled for only 1h and the completed reaction is achieved by subsequent
annealing. The correlations am... | 0603536v2 |
2006-03-23 | Charge Order in the Falicov-Kimball Model | We examine the spinless one-dimensional Falicov-Kimball model (FKM) below
half-filling, addressing both the binary alloy and valence transition
interpretations of the model. Using a non-perturbative technique, we derive an
effective Hamiltonian for the occupation of the localized orbitals, providing a
comprehensive des... | 0603628v1 |
2006-03-28 | Composition and temperature dependence of the thermoelectric power of Ni$_{2+x}$Mn$_{1-x}$Ga alloys | The thermoelectric power (TEP) measurements have been carried out to
investigate the changes in the electronic structure associated with the
intermartensitic and martensitic transitions in Ni$_{2+x}$Mn$_{1-x}$Ga (0 $\le$
x $\le$ 0.19). The samples have been characterized by a.c. magnetic
susceptibility measurements. Th... | 0603752v3 |
2006-03-29 | Resistivity and Magneto-Optical Evidence for Variable and Incomplete Connectivity in Dense, High Critical Current Density C-alloyed Magnesium Diboride | Carbon-doped magnesium diboride was fabricated from pre-reacted pure MgB2 by
mechanical alloying. The sample set had excellent critical current densities
Jc(8T,4.2K) ranging from 15-60 kA/cm2, depending on composition.
Magneto-optical imaging detected regions up to 0.5 mm in size which were nearly
100% dense with Jc 2-... | 0603800v1 |
2006-04-02 | The semiconductor-to-ferromagnetic-metal transition in FeSb2 | We propose FeSb2 to be a nearly ferromagnetic small gap semiconductor, hence
a direct analog of FeSi. We find that despite different compositions and
crystal structures, in the local density approximation with on-site Coulomb
repulsion correction (LDA+U) method magnetic and semiconducting solutions for
U=2.6 eV are ene... | 0604020v2 |
2006-04-05 | Critical behavior of the random-anisotropy model in the strong-anisotropy limit | We investigate the nature of the critical behavior of the random-anisotropy
Heisenberg model (RAM), which describes a magnetic system with random uniaxial
single-site anisotropy, such as some amorphous alloys of rare earths and
transition metals. In particular, we consider the strong-anisotropy limit
(SRAM), in which t... | 0604124v2 |
2006-04-06 | Correlated and uncorrelated nanoscale heterogeneities in L1_0 solid solutions and their signatures from local and extended probes | The phase coexistence of chemically ordered L1_0 and chemically disordered
structures within binary alloys is investigated, using the NiMn system as an
example. Theoretical and numerical predictions of the signatures one might
expect in data from local and extended probes are presented, in an attempt to
explain the pre... | 0604188v1 |
2006-06-13 | Phase Separation and the Phase Diagram in Cuprates Superconductors | We show that the main features of the cuprates superconductors phase diagram
can be derived considering the disorder as a key property of these materials.
Our basic point is that the high pseudogap line is an onset of phase separation
which generates compounds made up of regions with distinct doping levels. We
calculat... | 0606307v1 |
2006-06-13 | Fermi-liquid instabilities at magnetic quantum phase transitions | This review discusses instabilities of the Fermi-liquid state of conduction
electrons in metals with particular emphasis on magnetic quantum critical
points. Both the existing theoretical concepts and experimental data on
selected materials are presented; with the aim of assessing the validity of
presently available th... | 0606317v3 |
2006-06-28 | Mechanical alloying of Cu and Fe induced by severe plastic deformation of a Cu-Fe composite | A filamentary composite elaborated by cold drawing was processed by High
Pressure Torsion (HPT). The nanostructure resulting from this severe plastic
deformation (SPD) was investigated thanks to scanning electron microscopy,
transmission electron microscopy, X-ray diffraction and 3D atom probe. Although
the mutual solu... | 0606723v1 |
2006-07-04 | Influence of the driving mechanism on the response of systems with athermal dynamics: the example of the random-field Ising model | We investigate the influence of the driving mechanism on the hysteretic
response of systems with athermal dynamics. In the framework of local-mean
field theory at finite temperature (but neglecting thermallly activated
processes), we compare the rate-independent hysteresis loops obtained in the
random field Ising model... | 0607069v1 |
2006-07-06 | Spheroidal Particle Stability in Semi-Solid Processing | A model for diffusion-controlled spherical particle growth is presented and
solved numerically, showing how, on cooling at sufficient rate from a given
fraction solid, growth velocity first increases, and then decreases rapidly
when solute fields of adjacent particles overlap. An approximate analytical
solution for the... | 0607148v1 |
2006-07-10 | Influence of Preparation Process on Microstructure, Critical Current Density and Tc of MgB2/Fe/Cu Wires | The powder-in-tube MgB2 wires were prepared by high energy milling of Mg and
B powder. The powder was not mechanically alloyed for 2h short milling time.
However, the MgB2 grains in wires are very small (20 100nm) and resembled to
the dimple after post-heat treatment. The clear evidence for transcrystlline
fracture is ... | 0607223v1 |
2006-07-11 | Effect of lattice mismatch-induced strains on coupled diffusive and displacive phase transformations | Materials which can undergo slow diffusive transformations as well as fast
displacive transformations are studied using the phase-field method. The model
captures the essential features of the time-temperature-transformation (TTT)
diagrams, continuous cooling transformation (CCT) diagrams, and microstructure
formation ... | 0607276v2 |
2006-07-22 | Superconducting properties of nanocrystalline MgB$_2$ | Nanocrystalline MgB$_2$ produced by mechanical alloying has been shown to
exhibit enhanced superconducting properties such as increased pinning and
higher critical currents. However, the effects of the synthesis process on the
intrinsic superconducting properties have not been addressed yet. We have
investigated the su... | 0607578v1 |
2006-07-27 | Probing multiferroicity and spin-spin interactions via dielectric measurements on Y-doped HoMnO$_{3}$ in high magnetic fields | The magnetic field dependent phase diagram of the ferroelectric material
${\rm Ho}_{1-x}Y_{x}MnO_{3}$ has been investigated for x = 0, 0.6, and 0.8 for
fields directed along both the ab in-plane and c-axis basal plane directions.
Dielectric measurements are used to map out the re-entrant temperature-magnetic
field phas... | 0607742v1 |
2006-07-31 | Localization in 2D Quantum percolation | Quantum site percolation as a limiting case of binary alloy is studied
numerically in 2D within the tight-binding model. We address the transport
properties in all regimes - ballistic, diffusive (metallic), localized and
crossover between the latter two. Special attention is given to the region
close to the conduction ... | 0607818v2 |
2006-08-07 | Polarization-induced Rashba spin-orbit coupling in structurally symmetric III-Nitride quantum wells | The effective linear coupling coefficient and the total spin-splitting are
calculated in Ga- and N- face InGaN quantum wells. Alloy content, geometry, and
gate voltage affect an internal field and an electron density distribution in
the growth direction that has direct effect on a spin-splitting. The sign of
structural... | 0608179v1 |
2006-08-14 | Tricritical Phenomena at the Cerium $γ\to α$ Transition | The $\gamma \to \alpha$ isostructural transition in the
Ce$_{0.9-x}$La$_x$Th$_{0.1}$ system is measured as a function of La alloying
using specific heat, magnetic susceptibility, resistivity, thermal
expansivity/striction measurements. A line of discontinuous transitions, as
indicated by the change in volume, decreases... | 0608301v1 |
2006-08-15 | Feedback control of unstable cellular solidification fronts | We present a numerical and experimental study of feedback control of unstable
cellular patterns in directional solidification (DS). The sample, a dilute
binary alloy, solidifies in a 2D geometry under a control scheme which applies
local heating close to the cell tips which protrude ahead of the other. For the
experime... | 0608331v1 |
2006-08-23 | Electronic and optical properties of beryllium chalcogenides/silicon heterostructures | We have calculated electronic and optical properties of
Si/BeSe$_{0.41}$Te$_{0.59}$ heterostructures by a semiempirical $sp^{3}s^{*}$
tight-binding method. Tight-binding parameters and band bowing of
BeSe$_{0.41}$Te$_{0.59}$ are considered through a recent model for highly
mismatched semiconductor alloys. The band bowi... | 0608514v1 |
2006-08-24 | Heat conduction of single-walled carbon nanotube isotope-superlattice structures: A molecular dynamics study | Heat conduction of single-walled carbon nanotubes (SWNTs)
isotope-superlattice is investigated by means of classical molecular dynamics
simulations. Superlattice structures were formed by alternately connecting
SWNTs with different masses. On varying the superlattice period, the critical
value with minimum effective th... | 0608525v1 |
2006-08-24 | Observation of standard spin-switch effects in F/S/F trilayers with a strong ferromagnet | We have measured the superconducting transition temperature T_c of F/S/F
trilayers using Permalloy (Py=Ni_84 Fe_16) as a strongly polarized
ferromagnetic material. For a parallel (P) or anti-parallel (AP) alignment of
the magnetization directions of the outer ferromagnets, we observe a T_c
difference as large as 20 mK,... | 0608545v1 |
2006-08-30 | Atmospheric conditions and their effect on ball-milled magnesium diboride | Magnesium diboride bulk pellets were fabricated from pre-reacted MgB2 powder
ball milled with different amounts of exposure to air. Evidence of increased
electron scattering including increased resistivity, depressed Tc, and enhanced
Hc2 of the milled and heat treated samples were observed as a result of
increased cont... | 0608692v1 |
2006-09-05 | Dephasing of conduction electrons by magnetic impurities in Cu/Ni and Cu/Cr samples: Influence of spin-glass transition on the superconducting proximity effect | The dependence of the superconducting proximity effect on the amount of
magnetic impurities in the normal part of Andreev interferometers has been
studied experimentally. The dephasing rates obtained from fitting experimental
data to quasiclassical theory of the proximity effect are consistent with the
spin flip scatte... | 0609095v1 |
2006-09-06 | The chiral Anomalous Hall effect in re-entrant AuFe alloys | The Hall effect has been studied in a series of AuFe samples in the
re-entrant concentration range, as well as in part of the spin glass range. An
anomalous Hall contribution linked to the tilting of the local spins can be
identified, confirming theoretical predictions of a novel topological Hall term
induced when chir... | 0609124v2 |
2006-09-07 | Mn-doped Ga(As,P) and (Al,Ga)As ferromagnetic semiconductors | A remarkable progress towards functional ferromagnetic semiconductor
materials for spintronics has been achieved in p-type (Ga,Mn)As. Robust
hole-mediated ferromagnetism has, however, been observed also in other III-V
hosts such as antimonides, GaP or (Al,Ga)As which opens a wide area of
possibilities for optimizing th... | 0609158v1 |
2006-11-05 | High energy, high resolution photoelectron spectroscopy of Co2Mn(1-x)Fe(x)Si | This work reports on high resolution photoelectron spectroscopy for the
valence band of Co2Mn(1-x)Fe(x)Si (x=0,0.5,1) excited by photons of about 8 keV
energy. The measurements show a good agreement to calculations of the
electronic structure using the LDA+U scheme. It is shown that the high energy
spectra reveal the b... | 0611120v1 |
2006-11-09 | Local Atomic Structure of Martensitic Ni$_{2+x}$Mn$_{1-x}$Ga: An EXAFS Study | The local atomic structure of Ni$_{2+x}$Mn$_{1-x}$Ga with 0 $\le$ $x$ $\le$
0.16 alloys was explored using Mn and Ga K-edge Extended X-ray Absorption Fine
Structure (EXAFS) measurement. Inorder to study the atomic re-arrangements that
occur upon martensitic transformation, room temperature and low temperature
EXAFS wer... | 0611237v1 |
2007-01-04 | Controlling crystallization and its absence: Proteins, colloids and patchy models | The ability to control the crystallization behaviour (including its absence)
of particles, be they biomolecules such as globular proteins, inorganic
colloids, nanoparticles, or metal atoms in an alloy, is of both fundamental and
technological importance. Much can be learnt from the exquisite control that
biological sys... | 0701074v1 |
2007-01-30 | Thermodynamic Theory of Sintering and Swelling | The General Thermodynamic Theory of Sintering, formulated by the author in
1998 is given. This theory is applied to the problem of swelling of materials
under conditions of radiation. Driving forces, caused by the presence of the
evolution of heat in the volume of a sample (electric contact, hf, inductive
heating or pe... | 0701743v1 |
2007-02-04 | Studying Thermodynamics of Metastable States | Simple classical thermodynamic approach to the general description of
metastable states is presented. It makes possible to calculate the explicit
dependence of the Gibbs free energy on temperature, to calculate the heat
capacity, the thermodynamic barrier, dividing metastable and more stable
states, and the thermal exp... | 0702076v1 |
2007-03-16 | Best-Fit Ellipsoids of Atom-Probe Tomographic Data to Study Coalescence of Gamma Prime (L1_2) Precipitates in Ni-Al-Cr | An algorithm is presented to fit precipitates in atom probe tomographic data
sets as equivalent ellipsoids. Unlike previous techniques, which measure only
the radius of gyration, these ellipsoids retain the moments of inertia and
principle axes of the original precipitate, preserving crystallographic
orientational info... | 0703452v2 |
2007-03-19 | X-ray magnetic circular dichroism characterization of GaN/Ga1-xMnxN digital ferromagnetic heterostructure | We have investigated the magnetic properties of a GaN/Ga1-xMnxN (x = 0.1)
digital ferromagnetic heterostructure (DFH) showing ferromagnetic behavior
using soft x-ray absorption spectroscopy (XAS) and x-ray magnetic circular
dichroism (XMCD). The Mn L2,3-edge XAS spectra were similar to those of
Ga1-xMnxN random alloy t... | 0703477v3 |
2007-03-20 | Steric quenching of the switchable mirror effect Phys. Rev. B 75, 104109 (2007) | Scandium was substituted for yttrium to observe the effect of unit cell size
on the optical metal-to-insulator (MIT) transition in the Y_(1-z)Sc_(z)H_(x)
alloy system. The optical transmittance decreases significantly for z>0.10.
Simultaneous electrical resistivity measurements confirm the transition from
trihydride to... | 0703521v1 |
2007-02-28 | Numerical Model For Vibration Damping Resulting From the First Order Phase Transformations | A numerical model is constructed for modelling macroscale damping effects
induced by the first order martensite phase transformations in a shape memory
alloy rod. The model is constructed on the basis of the modified
Landau-Ginzburg theory that couples nonlinear mechanical and thermal fields.
The free energy function f... | 0702172v1 |
1993-06-03 | Elastic anomaly of heavy fermion systems in a crystalline field | An elastic anomaly, observed in the heavy fermi liquid state of Ce alloys
(for example, CeCu$_6$ and CeTe), is analyzed by using the infinite-$U$
Anderson lattice model. The four atomic energy levels are assumed for
f-electrons. Two of them are mutually degenerate. A small crystalline splitting
$2\Delta$ is assumed bet... | 9306004v1 |
2001-09-24 | Structure of Binary Sequences | The distribution of a given sequence in the set of all sequences with n ones
and m = M - n zeros are found by relating the problem to the partitions of a
natural number in m natural summands, taking into account the order. The
formulas obtained have many applications both in Physics and Mathematics.
Examples discussed ... | 0109182v1 |
2003-05-01 | Analysis of energetic models for rate-independent materials | We consider rate-independent models which are defined via two functionals:
the time-dependent energy-storage functional $\calI:[0,T]\ti X\to [0,\infty]$
and the dissipation distance $\calD:X\ti X\to[0,\infty]$. A function
$z:[0,T]\to X$ is called a solution of the {energetic model}, if for all $0\leq
s<t\leq T$ we have... | 0305014v1 |
2003-07-29 | Integrated density of states and Wegner estimates for random Schrödinger Operators | We survey recent results on spectral properties of random Schr\"odinger
operators. The focus is set on the integrated density of states (IDS). First we
present a proof of the existence of a self-averaging IDS which is general
enough to be applicable to random Schr\"odinger and Laplace-Beltrami operators
on manifolds. S... | 0307062v2 |
2003-10-17 | Lifshits tails caused by anisotropic decay: the emergence of a quantum-classical regime | We investigate Lifshits-tail behaviour of the integrated density of states
for a wide class of Schr\"odinger operators with positive random potentials.
The setting includes alloy-type and Poissonian random potentials. The
considered (single-site) impurity potentials $f: \mathbbm{R}^d \to [0, \infty[
$ decay at infinity... | 0310033v2 |
2004-12-21 | Bounds on the spectral shift function and the density of states | We study spectra of Schr\"odinger operators on $\RR^d$. First we consider a
pair of operators which differ by a compactly supported potential, as well as
the corresponding semigroups. We prove almost exponential decay of the singular
values $\mu_n$ of the difference of the semigroups as $n\to \infty$ and deduce
bounds ... | 0412078v1 |
2005-10-17 | Wegner Estimate for Indefinite Anderson Potentials: Some Recent Results and Applications | We review recent and give some new results on the spectral properties of
Schroedinger operators with a random potential of alloy type. Our point of
interest is the so called Wegner estimate in the case where the single site
potentials change sign. The indefinitness of the single site potential poses
certain difficultie... | 0510061v1 |
1995-06-29 | Spin-polarization-induced structural selectivity in Pd$_3X$ and Pt$_3X$ ($X=3d$) compounds | Spin-polarization is known to lead to important {\it magnetic} and {\it
optical} effects in open-shell atoms and elemental solids, but has rarely been
implicated in controlling {\it structural} selectivity in compounds and alloys.
Here we show that spin-polarized electronic structure calculations are crucial
for predic... | 9506007v1 |
1995-10-02 | Composition Dependence of the Structure and Electronic Properties of Liquid Ga-Se Alloys Studied by Ab Initio Molecular Dynamics Simulation | Ab initio molecular dynamics simulation is used to study the structure and
electronic properties of the liquid Ga-Se system at the three compositions
Ga$_2$Se, GaSe and Ga$_2$Se$_3$, and of the GaSe and Ga$_2$Se$_3$ crystals. The
calculated equilibrium structure of GaSe crystal agrees well with available
experimental d... | 9510001v1 |
1996-03-04 | Density functional theory study of Na at Al(111) and O at Ru(0001) | The success of density functional theory for the description of the
adsorption of atoms on surfaces is well established, and based on recent
calculations using gradient corrections, it has been shown that it also
describes well the dissociative adsorption of molecules at surfaces -
admittedly however, the data base for... | 9603001v1 |
1996-05-08 | Anomalies in He atom scattering spectra of the H-covered Mo(110) and W(110) surfaces | Helium atom scattering (HAS) studies of the H-covered Mo(110) and W(110)
surfaces reveal a twofold anomaly in the respective dispersion curves. In order
to explain this unusual behavior we performed density-functional theory
calculations of the atomic and electronic structure, the vibrational
properties, and the electr... | 9605002v1 |
1996-08-02 | Ab-initio study of the anomalies in the He atom scattering spectra of H/Mo(110) and H/W(110) | Helium atom scattering (HAS) studies of the H-covered Mo(110) and W(110)
surfaces reveal a twofold anomaly in the respective dispersion curves. In order
to explain this unusual behavior we performed density functional theory
calculations of the atomic and electronic structure, the vibrational
properties, and the spectr... | 9608002v1 |
1997-10-08 | Electrode thickness measurement of a Si(Li) detector for the SIXA array | Cathode electrodes of the Si(Li) detector elements of the SIXA X-ray
spectrometer array are formed by gold-palladium alloy contact layers. The
equivalent thickness of gold in one element was measured by observing the
characteristic L-shell X-rays of gold excited by monochromatised synchrotron
radiation with photon ener... | 9710009v1 |
2001-10-27 | Sucrose Solutions as Prospective Medium to Study the Vesicle Structure: SAXS and SANS study | The possibility to use sucrose solutions as medium for X-ray and neutron
small-angle scattering experiments has been explored for
dimyristoylphosphatidylcholine (DMPC) vesicles and mixed DMPC/C_(12)E_(8)
aggregates. The influence of sucrose concentration on phospholipid vesicles
size and polydispersity has been investi... | 0110078v1 |
2004-11-02 | Temperature dependent magnetic properties of FePt: effective spin Hamiltonian model | A model of magnetic interactions in the ordered ferromagnetic FePt is
proposed on the basis of first-principles calculations of non-collinear
magnetic configurations and shown to be capable of explaining recent
measurements of magnetic anisotropy energy (MAE). The site (Fe,Pt) resolved
contributions to the MAE have bee... | 0411020v1 |
2005-05-24 | Dependence of spontaneous emission rates of emitters on the refractive index of the surrounding medial | For emitters in a medium, different macroscopic or microscopic theoretical
models predict substantially different dependencies of the spontaneous emission
lifetime on refractive index. Various measurements have been carried out on
Eu$^{3+}$, Ce$^{3+}$ and Nd$^{3+}$ ions, and quantum dots in different
surrounding medial... | 0505166v1 |
2006-01-26 | The Effect of Gas Ion Bombardment on the Secondary Electron Yield of TiN, TiCN and TiZrV Coatings For Suppressing Collective Electron Effects in Storage Rings | In many accelerator storage rings running positively charged beams,
ionization of residual gas and secondary electron emission (SEE) in the beam
pipe will give rise to an electron cloud which can cause beam blow-up or loss
of the circulating beam. A preventative measure that suppresses electron cloud
formation is to en... | 0601206v2 |
2006-10-24 | Universal behavior of the electron g-factor in GaAs/AlGaAs quantum wells | The Zeeman splitting and the underlying value of the g-factor for conduction
band electrons in GaAs/Al_xGa_{1-x}As quantum wells have been measured by
spin-beat spectroscopy based on a time-resolved Kerr rotation technique. The
experimental data are in good agreement with theoretical predictions. The model
accurately a... | 0610216v1 |
2006-11-02 | Self consistent determination of plasmonic resonances in ternary nanocomposites | We have developed a self consistent technique to predict the behavior of
plasmon resonances in multi-component systems as a function of wavelength. This
approach, based on the tight lower bounds of the Bergman-Milton formulation, is
able to predict experimental optical data, including the positions, shifts and
shapes o... | 0611017v1 |
1998-01-07 | Large moments in external fields of cubic group symmetry | We predict that large moments $J$, placed into a crystal field with the cubic
point symmetry group, differ by their spectrum and magnetic properties. E. g.,
properties of the odd-integer moments are different from those of the
even-integer. The effect is due to Berry's phases gained by the moment, when it
tunnels betwe... | 9801010v1 |
2004-03-17 | Effect of electron-nuclear spin interactions on electron-spin qubits localized in self-assembled quantum dots | The effect of electron-nuclear spin interactions on qubit operations is
investigated for a qubit represented by the spin of an electron localized in a
self-assembled quantum dot. The localized electron wave function is evaluated
within the atomistic tight-binding model. The magnetic field generated by the
nuclear spins... | 0403122v1 |
2007-04-11 | A unified projection formalism for the Al-Pd-Mn quasicrystal Xi-approximants and their metadislocations | The approximants xi, xi' and xi'_n of the quasicrystal Al-Mn-Pd display most
interesting plastic properties as for example phason-induced deformation
processes (Klein, H., Audier, M., Boudard, M., de Boissieu, M., Beraha, L., and
Duneau, M., 1996, Phil. Mag. A, 73, 309.) or metadislocations (Klein, H.,
Feuerbacher, M.,... | 0704.1428v1 |
2007-04-17 | Ferromagnetic quantum critical point in URhGe doped with Ru | We have investigated the thermal, transport and magnetic properties of
URh$_{1-x}$Ru$_x$Ge alloys near the critical concentration $x_{cr} = 0.38$ for
the suppression of ferromagnetic order. The Curie temperature vanishes linearly
with $x$ and the ordered moment $m_0$ is suppressed in a continuous way. At
$x_{cr}$ the s... | 0704.2116v1 |
2007-05-04 | Monitoring Air Moisture with Laser Absorption Spectroscopy | Determination of air density and the quantitative estimates of water vapour
adsorbed or desorbed by the surface of mass standard, remain the principals
sources of uncertainties when weighing mass standard made from stainless steel
or super alloy. The classical method, for air density determination, use the so
called CI... | 0705.0616v1 |
2007-05-08 | Continuity properties of the integrated density of states on manifolds | We first analyze the integrated density of states (IDS) of periodic
Schr\"odinger operators on an amenable covering manifold. A criterion for the
continuity of the IDS at a prescribed energy is given along with examples of
operators with both continuous and discontinuous IDS'. Subsequently, alloy-type
perturbations o... | 0705.1079v1 |
2007-06-05 | Universal low-temperature behavior of the CePd_{1-x}Rh_x ferromagnet | The heavy-fermion metal CePd_{1-x}Rh_x evolves from ferromagnetism at x=0 to
a non-magnetic state at some critical concentration x_c. Utilizing the
quasiparticle picture and the concept of fermion condensation quantum phase
transition (FCQPT), we address the question about non-Fermi liquid (NFL)
behavior of ferromagnet... | 0706.0742v2 |
2007-06-10 | Low-temperature electron dephasing time in AuPd revisited | Ever since the first discoveries of the quantum-interference transport in
mesoscopic systems, the electron dephasing times, $\tau_\phi$, in the
concentrated AuPd alloys have been extensively measured. The samples were made
from different sources with different compositions, prepared by different
deposition methods, and... | 0706.1342v1 |
2007-06-29 | Orbital Order, Stripe Phases and Mott Transition in a Planar Model for Manganites | Understanding orbital ordered (OO) Mott insulating states lies at the heart
of a consistent resolution of the colossal magneto-resistance (CMR) observed in
manganites, where its melting induces a low-$T$ insulator-metal transition for
$0.25 \le x\le 0.45$. Motivated thereby, we study the OO states in a planar
model for... | 0706.4352v1 |
2007-07-17 | Positive and negative pressure effects on the magnetic ordering and the Kondo effect in the compound Ce2RhSi3 | The competition between magnetic ordering and the Kondo effect in Ce2RhSi3,
ordering antiferromagnetically at 7 K, is investigated by the measurements of
magnetization, heat capacity and electrical resistivity on the solid solutions,
Ce(2-x)La(x)RhSi3, Ce(2-y)Y(y)RhSi3, and Ce2RhSi(3-z)Ge(z), as well as by high
pressur... | 0707.2518v1 |
2007-07-20 | Ordering effects in diluted magnetic semiconductors | We review recently developed two-step approach for description of electronic
and magnetic properties of a new class of materials, the diluted magnetic
semiconductors. In the first step we construct, on the basis of the
state-of-the-art first-principles electronic structure calculations, the
effective Ising and Heisenbe... | 0707.3079v1 |
2007-07-27 | Magnetic Field Generation in Planets and Satellites by Natural Nuclear Fission Reactors | One of the most fundamental problems in physics has been to understand the
nature of the mechanism that generates the geomagnetic field and the magnetic
fields of other planets and satellites. For decades, the dynamo mechanism,
thought to be responsible for generating the geomagnetic field and other
planetary magnetic ... | 0707.4161v4 |
2007-08-01 | Phase diagram and magnetocaloric effect of CoMnGe_{1-x}Sn_{x} alloys | We propose the phase diagram of a new pseudo-ternary compound,
CoMnGe_{1-x}Sn_{x}, in the range x less than or equal to 0.1. Our phase diagram
is a result of magnetic and calometric measurements. We demonstrate the
appearance of a hysteretic magnetostructural phase transition in the range
x=0.04 to x=0.055, similar to ... | 0708.0204v1 |
2007-08-03 | Lifshitz asymptotics for Hamiltonians monotone in the randomness | In various aspects of the spectral analysis of random Schroedinger operators
monotonicity with respect to the randomness plays a key role. In particular,
both the continuity properties and the low energy behaviour of the integrated
density of states (IDS) are much better understood if such a monotonicity is
present in ... | 0708.0487v1 |
2007-08-09 | Coexistence of tetrahedral and octahedral-like sites in amorphous phase change materials | Chalcogenide alloys are materials of interest for optical recording and
non-volatile memories. We perform ab-initio molecular dynamics simulations
aiming at shading light onto the structure of amorphous Ge2Sb2Te5 (GST), the
prototypical material in this class. First principles simulations show that
amorphous GST obtain... | 0708.1302v2 |
2007-08-28 | Doniach diagram for ordered, disordered and underscreened Kondo lattices | The Doniach's diagram has been originally proposed to describe the
competition between the local Kondo effect and the intersite RKKY interactions
in cerium compounds. Here we discuss the extension of this diagram to different
variations of Kondo lattice model. We consider a) ordered cerium compounds
where the competiti... | 0708.3807v1 |
2007-08-29 | Solute trapping and diffusionless solidification in a binary system | Numerous experimental data on the rapid solidification of binary systems
exhibit the formation of metastable solid phases with the initial (nominal)
chemical composition. This fact is explained by complete solute trapping
leading to diffusionless (chemically partitionless) solidification at a finite
growth velocity of ... | 0708.3894v2 |
2007-08-29 | Thermodynamic properties of binary HCP solution phases from special quasirandom structures | Three different special quasirandom structures (SQS) of the substitutional
hcp $A_{1-x}B_x$ binary random solutions ($x=0.25$, 0.5, and 0.75) are
presented. These structures are able to mimic the most important pair and
multi-site correlation functions corresponding to perfectly random hcp
solutions at those compositio... | 0708.3995v1 |
2007-09-19 | Linearized force constants method for lattice dynamics in mixed semiconductors | A simple and accurate method of calculating phonon spectra in mixed
semiconductors alloys, on the basis of preliminarily (from first principles)
relaxed atomic structure, is proposed and tested for (Zn,Be)Se and (Ga,In)As
solid solutions. The method uses an observation that the interatomic force
constants, calculated a... | 0709.3104v1 |
2007-10-03 | Theory of stripe domains in magnetic shape memory alloys | The evolution of multivariant patterns in thin plates of magnetic shape
memory materials with an applied magnetic field was studied theoretically. A
geometrical domain-model is considered composed of straight stripe-like
martensite variants with constant internal magnetization (high anisotropy
limit) and magnetic domai... | 0710.0840v2 |
2007-10-19 | A fretting crack initiation prediction taking into account the surface roughness and the crack nucleation process volume | This paper presents an experimental study of the fretting crack nucleation
threshold, expressed in terms of loading conditions, with a cylinder/plane
contact. The studied material is a damage tolerant aluminium alloy widely used
in the aerospace application. Since in industrial problems, the surface quality
is often va... | 0710.3715v1 |
2007-11-02 | Origin of ferromagnetic response in diluted magnetic semiconductors and oxides | This paper reviews the present understanding of the origin of ferromagnetic
response of diluted magnetic semiconductors and diluted magnetic oxides as well
as in some nominally magnetically undoped materials. It is argued that these
systems can be grouped into four classes. To the first belong composite
materials in wh... | 0711.0340v1 |
2007-11-07 | Average Density of States in Disordered Graphene systems | In this paper, the average density of states (ADOS) with a binary alloy
disorder in disordered graphene systems are calculated based on the recursion
method. We observe an obvious resonant peak caused by interactions with
surrounding impurities and an anti-resonance dip in ADOS curves near the Dirac
point. We also find... | 0711.1018v1 |
2007-11-07 | Microstructure and mechanical properties of constrained shape-memory alloy nanograins and nanowires | We use the phase-field method to study the martensitic transformation at the
nanoscale. For nanosystems such as nanowires and nanograins embedded in a stiff
matrix, the geometric constraints and boundary conditions have an impact on
martensite formation, leading to new microstructures --such as dots aligned on
a square... | 0711.1084v1 |
2007-11-10 | Effect of mixed alkali-element substitution on structural and magnetic properties of praseodymium manganites Pr0.9(Na1-xKx)0.1MnO3 | The effect of cationic size mismatch at the A site at constant manganese
valence on the structural and magnetic properties of a perovskite-type
rare-earth manganate was investigated in the Pr0.9(Na1-xKx)0.1MnO3 solid
solution system (0 <= x < 1). All members of this solid solution series are
orthorhombic at room temper... | 0711.1578v1 |
2007-11-12 | Influence of disorder on the transport properties of heavy-fermion systems | The influence of substitutional disorder on the transport properties of
heavy-fermion systems is investigated. We extend the dynamical mean-field
theory treatment of the periodic Anderson model (PAM) to a coherent-potential
approximation for disordered strongly correlated electron systems. Considering
two distinct loca... | 0711.1768v2 |
2007-12-13 | Phase field simulations of coupled phase transformations in ferroelastic-ferroelastic nanocomposites | We use phase field simulations to study composites made of two different
ferroelastics (e.g., two types of martensite). The deformation of one material
due to a phase transformation can elastically affect the other constituent and
induce it to transform as well. We show that the phase transformation can then
occur abov... | 0712.2098v2 |
2007-12-17 | Electronic transport in AlMn(Si) and AlCuFe quasicrystals: Break-down of the semiclassical model | The semi-classical Bloch-Boltzmann theory is at the heart of our
understanding of conduction in solids, ranging from metals to semi-conductors.
Physical systems that are beyond the range of applicability of this theory are
thus of fundamental interest. It appears that in quasicrystals and related
complex metallic alloy... | 0712.2683v2 |
2007-12-17 | Spin tunneling in junctions with disordered ferromagnets | We provide compelling evidence to establish that, contrary to one's
elementary guess, the tunneling spin polarization (TSP) of amorphous CoFeB is
larger than that of highly textured fcc CoFeB. First principles atomic and
electronic structure calculations reveal striking agreement between the
measured TSP and the predic... | 0712.2722v1 |
2008-01-24 | Inverse approach to atomistic modeling: Applications to a-Si:H and g-GeSe2 | We discuss an inverse approach for atomistic modeling of glassy materials.
The focus is on structural modeling and electronic properties of hydrogenated
amorphous silicon and glassy GeSe2 alloy. The work is based upon a new approach
"experimentally constrained molecular relaxation (ECMR)". Unlike conventional
approache... | 0801.3685v1 |
2008-03-04 | Crossover between hydrodynamic and kinetic modes in binary liquid alloys | Inelastic x-ray scattering (IXS) measurements of the dynamic structure factor
in liquid Na57K43, sensitive to the atomic-scale coarse graining, reveal a
sound velocity value exceeding the long wavelength, continuum value and
indicate the coexistence of two phonon-like modes. Applying Generalized
Collective Mode (GCM) a... | 0803.0493v1 |
2008-03-18 | Combined experimental and theoretical investigation of the premartensitic transition in Ni$_2$MnGa | Ultraviolet-photoemission (UPS) measurements and supporting specific-heat,
thermal-expansion, resistivity and magnetic-moment measurements are reported
for the magnetic shape-memory alloy Ni$_2$MnGa over the temperature range $100K
< T < 250K$. All measurements detect clear signatures of the premartensitic
transition (... | 0803.2724v1 |
2008-05-01 | Absence of low-temperature dependence of the decay of 7Be and 198Au in metallic hosts | The electron-capture (EC) decay rate of 7Be in metallic Cu host and the
beta-decay rate of 198Au in the host alloy Al-Au have been measured
simultaneously at several temperatures, ranging from 0.350 K to 293 K. No
difference of the half-life of 198Au between 12.5 K and 293 K is observed to a
precision of 0.1%. By utili... | 0805.0024v1 |
2008-05-01 | Study of the effects induced by lead on the emulsion films of the OPERA experiment | The OPERA neutrino oscillation experiment is based on the use of the Emulsion
Cloud Chamber (ECC). In the OPERA ECC, nuclear emulsion films acting as very
high precision tracking detectors are interleaved with lead plates providing a
massive target for neutrino interactions. We report on studies related to the
effects ... | 0805.0123v2 |
2008-05-09 | General segregation and chemical ordering in bimetallic nanoclusters through atomistic view points | We predict general trends for surface segregation in a binary metal cluster
based on the difference between the atomic properties of the constituent
elements. Considering the attractive and repulsive contributions of the
cohesive energy of an atom in a cluster, energetically most favorable sites for
a guest atom on a p... | 0805.1396v1 |
2008-05-15 | Microstructure of precipitates and magnetic domain structure in an annealed Co38Ni33Al29 shape memory alloy | The microstructure of a CoNiAl FSMA was determined by conventional
transmission electron microscopy, electron diffraction studies together with
advanced microscopy techniques and in-situ Lorentz microscopy. 10 to 60 nm
sized rod-like precipitates of hcp $\epsilon$-Co were confirmed to be present
by HRTEM. The orientati... | 0805.2244v1 |
2008-05-19 | An efficient and accurate decomposition of the Fermi operator | We present a method to compute the Fermi function of the Hamiltonian for a
system of independent fermions, based on an exact decomposition of the
grand-canonical potential. This scheme does not rely on the localization of the
orbitals and is insensitive to ill-conditioned Hamiltonians. It lends itself
naturally to line... | 0805.2822v1 |
2008-06-02 | Thermodynamic stabilities of ternary metal borides: An ab initio guide for synthesizing layered superconductors | Density functional theory calculations have been used to identify stable
layered Li-$M$-B crystal structure phases derived from a recently proposed
binary metal-sandwich (MS) lithium monoboride superconductor. We show that the
MS lithium monoboride gains in stability when alloyed with electron-rich metal
diborides; the... | 0806.0061v1 |
2008-07-01 | Light matter in the core of the Earth: its identity, quantity and temperature using tricritical phenomena | Light elements in the iron-rich core of the Earth are important indicators
for the evolution of our planet. Their amount and distribution, and the
temperature in the core, are essential for understanding how the core and the
mantle interact and for modelling the geodynamo which generates the planetary
magnetic field. H... | 0807.0187v1 |
2008-07-23 | Metal-insulator transition by isovalent anion substitution in Ga1-xMnxAs: Implications to ferromagnetism | We have investigated the effect of partial isovalent anion substitution in
Ga1-xMnxAs on electrical transport and ferromagnetism. Substitution of only
2.4% of As by P induces a metal-insulator transition at a constant Mn doping of
x=0.046 while the replacement of 0.4 % As with N results in the crossover from
metal to i... | 0807.3722v1 |
2008-07-24 | Influence of defects on the electronic and magnetic properties of half-metallic CrAs, CrSe and CrSb zinc-blende compounds | We present an extended study of single impurity atoms and atomic swaps in
half-metallic CrAs, CrSb and CrSe zinc-blende compounds. Although the perfect
alloys present a rather large gap in the minority-spin band, all defects under
study, with the exception of void impurities at Cr and sp sites and Cr
impurities at sp s... | 0807.3836v1 |
2008-08-10 | 59-Co and 75-As NMR Investigation of Electron-Doped High Tc Superconductor BaFe(1.8)Co(0.2)As(2) (Tc = 22K) | We report an NMR investigation of the superconductivity in BaFe(2)As(2)
induced by Co doping (Tc=22K). We demonstrate that Co atoms form an alloy with
Fe atoms and donate carriers without creating localized moments. Our finding
strongly suggests that the underlying physics of iron-pnictide superconductors
is quite diff... | 0808.1420v2 |
2008-08-12 | Magnetism Driven by Anion Vacancies in Superconducting $α$--FeSe$_{1-x}$ | To study the microscopic electronic and magnetic interactions in the
substoichiometric iron chalcogenide FeSe$_{1-x}$ which is observed to
superconduct at x~1/8 up to $T_c$=27 K, we use first principles methods to
study the Se vacancy in this nearly magnetic FeSe system. The vacancy forms a
ferrimagnetic cluster of eig... | 0808.1733v2 |
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