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2008-08-12 | Observation of a continuous phase transition in a shape-memory alloy | Elastic neutron-scattering, inelastic x-ray scattering, specific-heat, and
pressure-dependent electrical transport measurements have been made on single
crystals of AuZn and Au_{0.52}Zn_{0.48} above and below their martensitic
transition temperatures (T_M=64K and 45K, respectively). In each composition,
elastic neutron... | 0808.1734v1 |
2008-08-17 | Application of the density functional theory to the fuel cell problem | The large-scale practical application of fuel cells in hydrogen economy is
possible only with a dramatic reduction of the cost coupled with a significant
improvement of the electrocatalytic properties of the electrodes. This goal can
be achieved through a rational design of new materials, which requires
understanding o... | 0808.2302v1 |
2008-08-30 | From diluted magnetic semiconductors to self-organized nanocolumns of GeMn in Germanium | While achieving high Curie temperatures (above room temperature) in diluted
magnetic semiconductors remains a challenge in the case of well controlled
homogeneous alloys, several systems characterized by a strongly inhomogeneous
incorporation of the magnetic component appear as promising. Incorporation of
manganese int... | 0809.0065v1 |
2008-09-22 | Tailoring the Magnetic Anisotropy in CoRh Nanoalloys: Experiment and Theory | The magnetic moments and magnetic anisotropy energy (MAE) of CoRh alloy
nanoparticles are determined experimentally and theoretically. Non-trivial
correlations between chemical order, magnetic order and MAE are revealed. A
remarkable non-monotonous dependence of the MAE as a function of composition
and chemical order i... | 0809.3638v1 |
2008-10-02 | Structural phase stability and Magnetism in Co2FeO4 spinel oxide | We report a correlation between structural phase stability and magnetic
properties of Co2FeO4 spinel oxide. We employed mechanical alloying and
subsequent annealing to obtain the desired samples. The particle size of the
samples changes from 25 nm to 45 nm. The structural phase separation of
samples, except sample anne... | 0810.0449v1 |
2008-10-09 | Atomistic spin dynamics of the CuMn spin glass alloy | We demonstrate the use of Langevin spin dynamics for studying dynamical
properties of an archetypical spin glass system. Simulations are performed on
CuMn (20% Mn) where we study the relaxation that follows a sudden quench of the
system to the low temperature phase. The system is modeled by a Heisenberg
Hamiltonian whe... | 0810.1645v1 |
2008-10-12 | Electronic and Magnetic Structure of the (LaMnO$_3$)$_{2n}$/(SrMnO$_3$)$_n$ Superlattices | We study the magnetic structure of the (LaMnO$_3$)$_{2n}$/(SrMnO$_3$)$_n$
superlattices from density-functional calculations. In agreement with the
experiments, we find that the magnetism changes with the layer thickness `n'.
The reason for the different magnetic structures is shown to be the varying
potential barrier ... | 0810.2126v1 |
2008-10-16 | Localization and Superconductivity in Doped Semiconductors | Motivated by the discovery of superconductivity in boron-doped (B-doped)
diamond, we investigate the localization and superconductivity in heavily doped
semiconductors. The competition between Anderson localization and s-wave
superconductivity is investigated from the microscopic point of view. The
effect of microscopi... | 0810.2915v3 |
2008-10-29 | Coarse grained Density Functional theory of order-disorder phase transitions in metallic alloys | The technological performances of metallic compounds are largely influenced
by atomic ordering. Although there is a general consensus that successful
theories of metallic systems should account for the quantum nature of the
electronic glue, existing non-perturbative high-temperature treatments are
based on effective cl... | 0810.5367v1 |
2008-11-14 | Observation of the magnetic domain structures in Cu$_{0,47}$Ni$_{0,53}$ thin films at low temperatures | We report on the first experimental visualization of domain structure in
films of weakly ferromagnetic Cu$_{0,47}$Ni$_{0,53}$ alloy with different
thickness at liquid helium temperatures. Improved high-resolution Bitter
decoration technique was used to map the magnetic contrast on the top of the
films well below the Cu... | 0811.2331v2 |
2008-12-04 | Superconductivity and short range order in metallic glasses Fe$_{x}$Ni$_{1-x}$Zr$_{2}$ | In amorphous superconductors, superconducting and vortex pinning properties
are strongly linked to the absence of long range order. Consequently,
superconductivity and vortex phases can be studied to probe the underlying
microstructure and order of the material. This is done here from resistance and
local magnetization... | 0812.1003v1 |
2008-12-06 | Voltage-Controlled Surface Magnetization of Itinerant Ferromagnet Ni_(1-x)Cu_x | We argue that surface magnetization of a metallic ferromagnet can be turned
on and off isothermally by an applied voltage. For this, the material's
electron subsystem must be close enough to the boundary between para- and
ferromagnetic regions on the electron density scale. For the 3d series, the
boundary is between Ni... | 0812.1309v1 |
2008-12-15 | Structural and magnetic properties of the (Bi2-xPrx)Ru2O7 pyrochlore solid solution (0 <= x <= 2) | We report a detailed study of structural and magnetic properties of the
pyrochlore-type (Bi2-xPrx)Ru2O7 series. Eleven compositions with 0 <= x <= 2
were prepared by solid state reaction at 1050 degrees C and found to form a
solid solution in the whole range of compositions. Structural refinements from
X-ray powder dif... | 0812.2759v1 |
2008-12-22 | Re-examination of half-metallic ferromagnetism for doped LaMnO3 in quasiparticle self-consistent $GW$ method | We apply the quasiparicle self-consistent $GW$ (\qsgw) method to a cubic
virtual-crystal alloy La$_{1-x}$Ba$_x$MnO$_3$ %(LBMO) as a theoretical
representative for colossal magnetoresistive perovskite manganites. The \qsgw\
predicts it as a fully-polarized half-metallic ferromagnet for a wide range of
$x$ and lattice co... | 0812.4294v2 |
2008-12-23 | Specific Resistance of Pd/Ir Interfaces | From measurements of the current-perpendicular-to-plane (CPP) total specific
resistance (AR = area times resistance) of sputtered Pd/Ir multilayers, we
derive the interface specific resistance, 2AR(Pd/Ir) = 1.02 +/- 0.06 fOhmm^2,
for this metal pair with closely similar lattice parameters. Assuming a single
fcc crystal... | 0812.4421v1 |
2009-01-09 | Critical Current Behavior in Josephson Junctions with the Weak Ferromagnet PdNi | We have studied the variation of critical current in
Superconductor/Ferromagnet/Superconductor (S/F/S) Josephson Junctions as a
function of ferromagnet thickness using a weakly-ferromagnetic alloy Pd82Ni12.
Measurements were performed for the thickness range 32 to 100 nm, over which
the critical current density decreas... | 0901.1321v1 |
2009-01-19 | Electronic Structures and Surface States of Topological Insulator Bi$_{1-x}$Sb$_{x}$ | We investigate the electronic structures of the alloyed Bi$_{1-x}$Sb$_x$
compounds based on first-principle calculations including spin-orbit coupling
(SOC), and calculate the surface states of semi-infinite systems using
maximally localized Wannier function (MLWF). From the calculated results, we
analyze the topologic... | 0901.2762v2 |
2009-01-22 | Ferromagnetism in two band metals: Combined effect of Coulomb correlation, hybridization and band widths | We study the possibility of ferromagnetism in metals. The metal is described
by two hybridized bands one of which includes Hubbard correlation whereas the
other is uncorrelated. We parametrize the ratio of the band widths and their
centers as well. The original Hamiltonian is transformed in an effective and
simpler one... | 0901.3517v2 |
2009-01-29 | The melting behavior of lutetium aluminum perovskite LuAlO3 | DTA measurements with mixtures of aluminum oxide and lutetium oxide around
the 1:1 perovskite composition were performed up to 1970 deg. C. A peak with
onset 1901 deg C was due to the melting of the eutectic Lu4Al2O9 (monoclinic
phase) and LuAlO3 (perovskite). Neither peritectic melting of the perovskite
nor its decomp... | 0901.4654v3 |
2009-02-11 | Diffusion-controlled phase growth on dislocations | We treat the problem of diffusion of solute atoms around screw dislocations.
In particular, we express and solve the diffusion equation, in radial symmetry,
in an elastic field of a screw dislocation subject to the flux conservation
boundary condition at the interface of a new phase. We consider an incoherent
second-ph... | 0902.1841v1 |
2009-03-09 | Cohesive and magnetic properties of grain boundaries in bcc Fe with Cr additions | Structural, cohesive, and magnetic properties of two symmetric $\Sigma3(111)$
and $\Sigma5(210)$ tilt grain boundaries (GBs) in pure bcc Fe and in dilute
FeCr alloys are studied from first principles. Different concentration and
position of Cr solute atoms are considered. We found that Cr atoms placed in
the GB interst... | 0903.1618v2 |
2009-03-10 | Reproducibility of room temperature ferromagnetism in Zn0.95Mn0.05O and its understanding | The present work reproduces the room temperature ferromagnetism by doping
magnetic Mn atoms in diamagnetic ZnO. The ferromagnetic ordering is extended up
to 640 K in mechanical milled Zn0.95Mn0.05O samples. The bulk and
nanocrystalline samples are stabilized in hexagonal crystal structure with
space group p63mc. The gr... | 0903.1691v1 |
2009-04-22 | Static critical exponents of the ferromagnetic transition in spin glass re-entrant systems | The static critical phenomenology near the Curie temperature of the
re-entrant metallic alloys Au_0.81Fe_0.19, Ni_0.78Mn_0.22, Ni_0.79Mn_0.21 and
amorphous a-Fe_0.98Zr_0.08 is studied using a variety of experimental
techniques and methods of analysis. We have generally found that the values for
the exponents alpha, bet... | 0904.3481v1 |
2009-05-06 | Josephson tunnel junctions with ferromagnetic $\Fe_{0.75}\Co_{0.25}$ barriers | Josephson tunnel junctions with the strong ferromagnetic alloy
$\Fe_{0.75}\Co_{0.25}$ as the barrier material were studied. The junctions were
prepared with high quality down to a thickness range of a few monolayers of
Fe-Co. An oscillation length of $\xi_{F2}\approx 0.79\:{\rm {nm}}$ between 0
and $\pi$-Josephson phas... | 0905.0761v1 |
2009-05-06 | Scaling in Plateau-to-Plateau Transition: A Direct Connection of Quantum Hall Systems with Anderson Localization Model | The quantum Hall plateau transition was studied at temperatures down to 1 mK
in a random alloy disordered high mobility two-dimensional electron gas. A
perfect power-law scaling with \kappa=0.42 was observed from 1.2K down to 12mK.
This perfect scaling terminates sharply at a saturation temperature of
T_s~10mK. The sat... | 0905.0885v1 |
2009-05-08 | A cluster model with random anisotropy for hysteresis jumps in CeNi$_{1-x}$Cu$_{x}$ alloys | Some Cerium compounds exhibit hysteresis cycles with sharp macroscopic jumps
in the magnetization at very low temperatures. This effect is attributed to the
formation of clusters in which the anisotropy competes with the applied
magnetic field. Here, we present a simple model where a lattice of
ferromagnetically couple... | 0905.1219v1 |
2009-05-13 | Quantum transport in weakly coupled superlattices at low temperature | We report on the study of the electrical current flowing in weakly coupled
superlattice (SL) structures under an applied electric field at very low
temperature, i.e. in the tunneling regime. This low temperature transport is
characterized by an extremely low tunneling probability between adjacent wells.
Experimentally,... | 0905.2062v3 |
2009-06-18 | Origin of large moments in Mn$_x$Si$_{1-x}$ at small x | Recently, the magnetic moment/Mn, $M$, in Mn$_x$Si$_{1-x}$ was measured to be
5.0 $\mu_B$/Mn, at $x$ =0.1%. To understand this observed $M$, we investigate
several Mn$_x$Si$_{1-x}$ models of alloys using first-principles density
functional methods. The only model giving $M = 5.0$ was a 513-atom cell having
the Mn at a ... | 0906.3502v1 |
2009-06-18 | Intrinsic exchange bias in Zn$_x$Mn$_{3-x}$O$_4$ ($x \leq 1$) solid solutions | Bulk specimens of the hetaerolite solid solution Zn$_x$Mn$_{3-x}$O$_4$, with
$x$ = 0, 0.25, 0.5, 0.75, and 1 have been prepared as homogeneous, phase-pure
polycrystalline samples as ascertained by neutron diffraction measurements.
Samples with $x$ = 0.25, 0.5, and 0.75 exhibit shifted magnetic hysteresis
loops at low t... | 0906.3534v2 |
2009-06-24 | Detection of sub-lattice magnetism in sigma-phase Fe-V compounds by zero-field NMR | The first successful measurements of a sub-lattice magnetism with 51V NMR
techniques in the sigma-phase Fe(100-x)Vx alloys with x = 34.4, 39.9 and 47.9
are reported. Vanadium atoms present on all five crystallographic sites are
magnetic. Their magnetic properties are characteristic of a given site, which
strongly depen... | 0906.4458v2 |
2009-07-02 | Moessbauer spectroscopy evidence for the lack of iron magnetic moment in superconducting FeSe | Superconducting FeSe has been investigated by measurements of the magnetic
susceptibility versus temperature and Moessbauer spectroscopy at various
temperatures including strong external magnetic fields applied to the absorber.
It was found that isomer shift exhibits sharply defined increase at about 105 K
leading to t... | 0907.0383v2 |
2009-07-09 | Importance of the atom-pair bond in metallic alloying | Rajasekharan and Girgis reported that binary systems with intermetallic
compounds of a particular crystal structure form a straight line on a map using
Miedema parameters. In this paper, the universality of that observation is
examined. Observations from a study of 143 binary systems that crystallize in
six different c... | 0907.1589v1 |
2009-07-14 | Upstanding Rashba spin in honeycomb lattices: Electrically reversible surface spin polarization | The spin-split states subject to Rashba spin-orbit coupling in
two-dimensional systems have long been accepted as pointing inplane and
perpendicular to the corresponding wave vectors. This is in general true for
free electron model, but exceptions do exist elsewhere. Within the
tight-binding model, we unveil the unusua... | 0907.2411v3 |
2009-07-23 | Electrostatic co-assembly of magnetic nanoparticles and fluorescent nanospheres: a versatile approach toward bimodal nanorods | The elaboration of multimodal nanoparticles stimulates tremendous interest
owing to their numerous potentialities in many applicative fields like
optoelectronics, photonics and especially bioimaging. The concomitant
association of various properties (optical, electrochemical, magnetic) allows
for the use of complementa... | 0907.3979v1 |
2009-08-10 | Magnetic field dependence of the antiferromagnetic phase transitions in Co-doped YbRh_2Si_2 | We present first specific-heat data of the alloy Yb(Rh_(1-x)Co_x)_2Si_2 at
intermediate Co-contents x=0.18, 0.27, and 0.68. The results already point to a
complex magnetic phase diagram as a function of composition. Co-doping of
YbRh_2Si_2 (T_N^{x=0}=72 mK) stabilizes the magnetic phase due to the volume
decrease of th... | 0908.1299v1 |
2009-08-23 | A mesoscale granular model for the mechanical behavior of alloys during solidification | We present a two-dimensional granular model for the mechanical behavior of an
ensemble of globular grains, during solidification. The grain structure is
produced by a Voronoi tessellation based on an array of predefined nuclei. We
consider the fluid flow caused by grain movement and solidification shrinkage
in the netw... | 0908.3311v1 |
2009-09-02 | Self-Excited Vibrations in Turning: Efforts Torsor and Average Friction Coefficient Analysis | An experimental device in turning including, in particular, a six-component
dynamometer is exploited to measure the complete torque of cutting forces in a
case of self-excited vibrations. For the tests, the tool used is type TNMA 16
04 12 carbide not covered (nuance carbide-SUMITIMO ELECTRIC), without chip
breeze. The ... | 0909.0331v1 |
2009-09-04 | Electronic structure of the sigma-phase in paramagnetic Fe-V alloys. Experimental and theoretical study | The electronic structure of $\sigma$-phase Fe$_{100-x}$V$_x$ compounds with
33.3 $\le x \le 60.0$ was calculated from the charge self-consistent
Korringa-Kohn-Rostoker method. For the first time, charge densities $\rho_A(0)$
and electric field gradients were determined at Fe nuclei, that occupy five
nonequivalent latti... | 0909.0839v1 |
2009-09-09 | Stability and magnetic properties of Mn-substituted ScN from first principles | We present a spin density functional theory (DFT) study for semiconducting
ScN and Mn-substituted ScN.
Their structural and magnetic properties have been investigated using the all
electrons augmented spherical wave method (ASW) with a generalized gradient GGA
functional for treating the effects of exchange and corre... | 0909.1676v1 |
2009-09-21 | Experimental probing of the interplay between ferromagnetism and localisation in (Ga,Mn)As | The question whether the Anderson-Mott localisation enhances or reduces
magnetic correlations is central to the physics of magnetic alloys.
Particularly intriguing is the case of (Ga,Mn)As and related magnetic
semiconductors, for which diverging theoretical scenarios have been proposed.
Here, by direct magnetisation me... | 0909.3694v1 |
2009-10-11 | Magnetic and electrical properties of RCo2Mn (R=Ho, Er) compounds | The RCo2Mn (R= Ho and Er) alloys, crystallizing in the cubic MgCu2-type
structure, are isostructural to RCo2 compounds. The excess Mn occupies both the
R and the Co atomic positions. Magnetic, electrical and heat capacity
measurements have been done in these comounds. The Curie temperature is found
to be 248 K and 222 ... | 0910.2001v1 |
2009-10-14 | Discovery of a binary icosahedral quasicrystal in Sc$_12$Zn$_88$ | We report the discovery of a new binary icosahedral phase in a Sc-Zn alloy
obtained through solution-growth, producing millimeter-sized, facetted, single
grain, quasicrystals that exhibit different growth morphologies, pentagonal
dodecahedra and rhombic triacontahedra, under only marginally different growth
conditions.... | 0910.2507v1 |
2009-10-19 | Development of the critical exponent at the antiferromagnetic phase transition of YbRh2Si2 under chemical pressure | We present specific-heat measurements in the vicinity of the
antiferromagnetic phase transition on single crystals of the alloy
Yb(Rh_{1-x}Co_x)2Si2 for x<= 0.38. This study was motivated by the violation of
critical universality in the undoped YbRh2Si2 (Krellner et al., Phys. Rev.
Lett. 102, 196402) where we have foun... | 0910.3567v1 |
2009-10-19 | Electronic Structure, Localization and Spin-State Transition in Cu-substituted FeSe: Fe$_{1-x}$Cu$_x$Se | We report density functional studies of the Fe$_{1-x}$Cu$_x$Se alloy done
using supercell and coherent potential approximation methods. Magnetic behavior
was investigated using the disordered local moment approach. We find that Cu
occurs in a nominal $d^{10}$ configuration and is highly disruptive to the
electronic str... | 0910.3599v1 |
2009-10-23 | Adsorbate-induced Restructuring of Pb mesas Grown on Vicinal Si(111) in the Quantum Regime | Using scanning tunneling microscopy and spectroscopy, we demonstrate that the
adsorption of a minute amount of Cs on a Pb mesa grown in the quantum regime
can induce dramatic morphological changes of the mesa, characterized by the
appearance of populous monatomic-layer-high Pb nano-islands on top of the mesa.
The edges... | 0910.4470v2 |
2009-11-16 | Searching for Better Plasmonic Materials | Plasmonics is a research area merging the fields of optics and
nanoelectronics by confining light with relatively large free-space wavelength
to the nanometer scale - thereby enabling a family of novel devices. Current
plasmonic devices at telecommunication and optical frequencies face significant
challenges due to los... | 0911.2737v4 |
2009-11-21 | Studies of single doping of Mn and Fe in Si to deduce simple guidelines in selecting transition metal elements for growing Si-based spintronic materials | Single dopings of Mn and Fe in Si are investigated using 8-, 64-, and
216-atom supercells and a first-principles method based on density functional
theory. Between the two transition metal elements (TMEs), atom sizes play an
essential role in determining the contraction or the expansion of neighboring
atoms around the ... | 0911.4152v2 |
2009-12-24 | Inhomogeneity of Magnesium Diboride Structure and its Effect on Critical Current Density | The influence of the oxygen segregation into Mg-B-O inclusions (which are
oxygen enriched as compared to the matrix material) and the formation of boron
enriched phases (with near MgB12 composition) in MgB2 structure on pinning in
magnesium diboride and the effect of SiC and Ti alloying on the formation of
structural i... | 0912.4903v1 |
2010-01-08 | Self-organized synthesis of patterned magnetic nanostructures with in-plane and perpendicular to the plane magnetization | Patterned arrays of ferromagnetic nanoparticles of Co, Ni, and Fe_{\text{50}}
Co_{\text{50}} have been synthesized from their ultrathin metal films on
SiO_{\text{2}} substrate by nanosecond laser-induced self-organization. The
morphology, nanostructure, and magnetic behavior of the nanoparticle arrays
were investigated... | 1001.1328v1 |
2010-01-18 | Design and optimization of plasmonic-based metal-dielectric nanocomposite materials for energy applications | Metallic nanoparticles embedded in dielectrics permit enhanced capture of
light at specific wavelengths through excitation of plasmons, i.e. the quanta
of coherent and collective oscillations of large concentrations of nearly free
electrons. In order to maximize the potential of such enhanced absorption in
useful tasks... | 1001.3114v1 |
2010-01-18 | Non-constant crack tip opening angle and negligible crack tunneling of brittle fracture in Al: A first-principles prediction | Numerous measurements showed that the crack tip opening angle (CTOA) is
nearly constant upon stable ductile fracture in Al alloys which widely used in
modern transportation industry. The atomic structure of the very tip of a crack
front has remained unknown, however. We have carried out a first-principles
density funct... | 1001.3168v1 |
2010-01-27 | Interference of spin states in photoemission from Sb/Ag(111) | Using a three-dimensional spin polarimeter we have gathered evidence for the
interference of spin states in photoemission from the surface alloy Sb/Ag(111).
This system features a small Rashba-type spin-splitting of a size comparable to
the linewidth of the quasiparticles, thus causing an intrinsic overlap between
stat... | 1001.4927v1 |
2010-01-28 | Magnetic phase stability of monolayers: Fe on Ta(x)W(1-x) (001) random alloy as a case study | We present a new approach to study the magnetic phase stability of magnetic
overlayers on nonmagnetic substrates. The exchange integrals among magnetic
atoms in the overlayer are estimated in the framework of the adiabatic
approximation and used to construct the effective classical two-dimensional
Heisenberg Hamiltonia... | 1001.5126v1 |
2010-02-04 | A plasticity model with yield surface distortion for non proportional loading | In order to enhance the modeling of metallic materials behavior in non
proportional loadings, a modification of the classical elastic-plastic models
including distortion of the yield surface is proposed. The new yield criterion
uses the same norm as in the classical von Mises based criteria, and a
"distorted stress" Sd... | 1002.0914v1 |
2010-02-04 | Neutron scattering and muSR investigations of the spin liquid state with quenched disorder in LuCuGaO4 | LuCuGaO4 has magnetic Cu2+ and diamagnetic Ga3+ ions distributed on a
triangular bilayer and is suggested to undergo a spin-glass transition with T_g
approximately 0.4 K. Using muSR and neutron scattering measurements, we show
that at low temperature the spins form a short-range correlated state with spin
fluctuations ... | 1002.0975v2 |
2010-02-12 | Different Evolution of Intrinsic Gap in Kondo Semiconductors SmB6 and YbB12 | Dependence of the spectral functions on temperature and rare-earth
substitution was examined in detail for Kondo semiconductor alloys Sm1-xEuxB6
and Yb1-xLuxB12 by bulk-sensitive photoemission. It is found that the 4f
lattice coherence and intrinsic (small) energy gap are robust for SmB6 against
the Eu substitution up ... | 1002.2530v1 |
2010-02-15 | Structure maps for hcp metals from first principles calculations | The ability to predict the existence and crystal type of ordered structures
of materials from their components is a major challenge of current materials
research. Empirical methods use experimental data to construct structure maps
and make predictions based on clustering of simple physical parameters. Their
usefulness ... | 1002.2822v1 |
2010-02-18 | Quantum well infrared photodetectors hardiness to the non ideality of the energy band profile | We report results on the effect of a non-sharp and disordered potential in
Quantum Well Infrared Photodetectors (QWIP). Scanning electronic transmission
microscopy is used to measure the alloy profile of the structure which is shown
to present a gradient of composition along the growth axis. Those measurements
are used... | 1002.3543v2 |
2010-03-01 | Magnetic field effect on Fe-induced short-range magnetic correlation and electrical conductivity in Bi$_{1.75}$Pb$_{0.35}$Sr$_{1.90}$Cu$_{0.91}$Fe$_{0.09}$O$_{6+y}$ | We report electrical resistivity measurements and neutron diffraction studies
under magnetic fields of
Bi$_{1.75}$Pb$_{0.35}$Sr$_{1.90}$Cu$_{0.91}$Fe$_{0.09}$O$_{6+y}$, in which hole
carriers are overdoped. This compound shows short-range incommensurate magnetic
correlation with incommensurability $\delta=0.21$, wherea... | 1003.0262v2 |
2010-03-05 | Comment on "Doping Driven ($π,0$) Nesting and Magnetic Properties of Fe$_{1+x}$Te Superconductors" [Phys. Rev. Lett. 103, 067001 (2009)] | In this Comment, using Korringa-Kohn-Rostoker coherent-potential
approximation method in the atomic-sphere approximation (KKR-ASA CPA) to
describe the effects of disorder due to excess Fe in FeTe alloys, we show that
(i) the rigid-band approximation is inadequate to describe the effects of
disorder and its application ... | 1003.1186v1 |
2010-03-05 | Diffuse-interface model for nanopatterning induced by self-sustained ion etch masking | We construct a simple phenomenological diffuse-interface model for
composition-induced nanopatterning during ion sputtering of alloys. In
simulations, this model reproduces without difficulties the high-aspect ratio
structures and tilted pillars observed in experiments. We investigate the time
evolution of the pillar h... | 1003.1274v2 |
2010-03-12 | Correlated electrons in the presence of disorder | Several new aspects of the subtle interplay between electronic correlations
and disorder are reviewed. First, the dynamical mean-field theory
(DMFT)together with the geometrically averaged ("typical") local density of
states is employed to compute the ground state phase diagram of the
Anderson-Hubbard model at half-fil... | 1003.2498v2 |
2010-03-22 | Cell dynamics modeling of phase transformation and metastable phase formation | The phase transition kinetics in three phase systems was investigated using
the numerically efficient cell dynamics method. A phasefield model with a
simple analytical free energy and single order parameter was used to study the
kinetics and the thermodynamics of a three-phase system. This free energy is
able to achiev... | 1003.4041v1 |
2010-03-19 | Effects of a radially varying electrical conductivity on 3D numerical dynamos | The transition from liquid metal to silicate rock in the cores of the
terrestrial planets is likely to be accompanied by a gradient in the
composition of the outer core liquid. The electrical conductivity of a volatile
enriched liquid alloy can be substantially lower than a light-element-depleted
fluid found close to t... | 1003.4192v1 |
2010-03-23 | Pre-edge XANES structure of Mn in (Ga,Mn)As | The X-ray absorption near-edge structure (XANES) at the Mn K-edge in the
(Ga,Mn)As magnetic semiconductor was simulated using the full potential
linearized augmented plane wave (FLAPW) method including the core-hole effect.
The calculations were performed in the supercell scheme for a substitutional
and two tetrahedral... | 1003.4390v1 |
2010-03-26 | First Principles Studies on 3-Dimentional Strong Topological Insulators: Bi2Te3, Bi2Se3 and Sb2Te3 | Bi2Se3, Bi2Te3 and Sb2Te3 compounds are recently predicted to be
3-dimentional (3D) strong topological insulators. In this paper, based on
ab-initio calculations, we study in detail the topological nature and the
surface states of this family compounds. The penetration depth and the
spin-resolved Fermi surfaces of the ... | 1003.5082v1 |
2010-03-27 | Cryogenic scanning force microscopy of quantum Hall samples: Adiabatic transport originating in anisotropic depletion at contact interfaces | Anisotropic magneto resistances and intrinsic adiabatic transport features
are generated on quantum Hall samples based on an (Al,Ga)As/GaAs
heterostructure with alloyed Au/Ge/Ni contacts. We succeed to probe the
microscopic origin of these transport features with a cryogenic scanning force
microscope (SFM) by measuring... | 1003.5271v1 |
2010-04-12 | Nonequilibrium phase transitions and tricriticality in a three-dimensional lattice system with random-field competing kinetics | We study a nonequilibrium Ising model that stochastically evolves under the
simultaneous operation of several spin-flip mechanisms. In other words, the
local magnetic fields change sign randomly with time due to competing kinetics.
This dynamics models a fast and random diffusion of disorder that takes place
in dilute ... | 1004.2065v1 |
2010-04-24 | The Realization of Artificial Kondo Lattices in Nanostructured Arrays | The interplay of magnetic energies in a Kondo lattice is the underlying
physics of a heavy fermion system. Creating an artificial Kondo lattice system
by localizing the moments in an ordered metallic array provides a prototype
system to tune and study the energetic interplay while avoiding the
complications introduced ... | 1004.4276v1 |
2010-05-04 | Fe ion doping effect on electrical and magnetic properties of La0.7Ca0.3Mn1-xFexO3 x = 0.0 to 1.0 | Here we report the structural, electrical and magnetic properties of Fe doped
La0.7Ca0.3Mn1-xFexO3 with x = 0.0 to 1.0 prepared by conventional solid state
reaction method. Simulated data on XRD shows an increase in volume with an
increase in Fe ion concentration. XPS supports that Fe3+ ions directly
substitute Mn3+ io... | 1005.0436v2 |
2010-05-15 | On the prediction of shrinkage defects by thermal criterion functions | The indirect prediction of shrinkage induced solidification defects is
considered in this study. The previously suggested criterion function methods,
in particular the Pellini and Niyama criteria are analyzed in details, and
their shortcomings are shown as a result of our analysis (e.g. the
scale/shape-dependency of cr... | 1005.2706v1 |
2010-05-26 | Spin diffusion in the Mn2+ ion system of II-VI diluted magnetic semiconductor heterostructures | The magnetization dynamics in diluted magnetic semiconductor heterostructures
based on (Zn,Mn)Se and (Cd,Mn)Te has been studied experimentally by optical
methods and simulated numerically. In the samples with nonhomogeneous magnetic
ion distribution this dynamics is contributed by spin-lattice relaxation and
spin diffu... | 1005.4862v1 |
2010-06-01 | Irreversibility of field-induced magnetostructural transition in NiCoMnSb shape memory alloy revealed by magnetization, transport and heat capacity studies | The effects of magnetic field on the martensitic transition have been studied
in Ni45Co5Mn38Sb12. We find a large field-induced irreversibility in this
system, as revealed by the field dependence of resistivity, magnetization, and
heat capacity data. At the critical temperature, the field-induced conversion
of the mart... | 1006.0060v1 |
2010-06-07 | Carrier localization mechanisms in InGaN/GaN quantum wells | Localization lengths of the electrons and holes in InGaN/GaN quantum wells
have been calculated using numerical solutions of the effective mass
Schr\"odinger equation. We have treated the distribution of indium atoms as
random and found that the resultant fluctuations in alloy concentration can
localize the carriers. B... | 1006.1232v1 |
2010-06-15 | Field-induced multiple metamagnetization in phase transition from paramagnetic austenite to ferromagnetic martensite in MnNi1-xFexGe | Tailoring the phase stability and magnetic structure by combining the
antiferromagnetic MnNiGe martensite with ferromagnetic MnFeGe austenite, a
magnetic-field-induced martensitic transformation has been achieved in
MnNi1-xFexGe system. The doped Fe enables the isolated structural and magnetic
transitions of MnNiGe to ... | 1006.2907v1 |
2010-06-22 | Distorted wurtzite unit cells: Determination of lattice parameters of non-polar a-plane AlGaN and estimation of solid phase Al content | Unlike c-plane nitrides, ``non-polar" nitrides grown in e.g. the a-plane or
m-plane orientation encounter anisotropic in-plane strain due to the anisotropy
in the lattice and thermal mismatch with the substrate or buffer layer. Such
anisotropic strain results in a distortion of the wurtzite unit cell and
creates diffic... | 1006.4262v1 |
2010-06-23 | Novel Properties of Frustrated Low Dimensional Magnets with Pentagonal Symmetry | In the context of magnetism, frustration arises when a group of spins cannot
find a configuration that minimizes all of their pairwise interactions
simultaneously. We consider the effects of the geometric frustration that
arises in a structure having pentagonal loops. Such five-fold loops can be
expected to occur natur... | 1006.4515v1 |
2010-06-30 | Large quantum dots with small oscillator strength | We have measured the oscillator strength and quantum efficiency of excitons
confined in large InGaAs quantum dots by recording the spontaneous emission
decay rate while systematically varying the distance between the quantum dots
and a semiconductor-air interface. The size of the quantum dots is measured by
in-plane tr... | 1006.5796v1 |
2010-07-20 | RKKY interaction in a disordered two-dimensional electron gas with Rashba and Dresselhaus spin-orbit couplings | We study theoretically the statistical properties of the
Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between localized magnetic
moments in a disordered two-dimensional electron gas with both Rashba and
Dresselhaus spin-orbit couplings. Averaging over disorder, the static spin
susceptibility tensor is evaluated dia... | 1007.3506v2 |
2010-07-22 | Strongly suppressed 1/f noise and enhanced magnetoresistance in epitaxial Fe-V/MgO/Fe magnetic tunnel junctions | Alloying Fe electrodes with V, through reduced FeV/MgO interface mismatch in
epitaxial magnetic tunnel junctions with MgO barriers, notably suppresses both
nonmagnetic (parallel) and magnetic (antiparallel) state 1/f noise and enhances
tunnelling magnetoresistance (TMR). A comparative study of the room temperature
elec... | 1007.3941v1 |
2010-07-26 | Phase-Field Reaction-Pathway Kinetics of Martensitic Transformations in a Model Fe3Ni Alloy | A three-dimensional phase-field approach to martensitic transformations that
uses reaction pathways in place of a Landau potential is introduced and applied
to a model of Fe3Ni. Pathway branching involves an unbounded set of variants
through duplication and rotations by the rotation point groups of the austenite
and ma... | 1007.4515v1 |
2010-07-27 | Few-electron quantum dots in III-V ternary alloys: role of fluctuations | We study experimentally the electron transport properties of gated quantum
dots formed in InGaAs/InP and InAsP/InP quantum well structures grown by
chemical-beam epitaxy. For the case of the InGaAs quantum well, quantum dots
form directly underneath narrow gate electrodes due to potential fluctuations.
We measure the C... | 1007.4849v2 |
2010-07-28 | Structural and dynamical study of moment localization in beta-Mn(1-x)In(x) | We have used neutron scattering and muon spin relaxation (muSR) to
investigate the structural and magnetic properties of the beta-phase of
elemental manganese doped with dilute amounts of indium. beta-Mn is an example
of a topologically frustrated antiferromagnetically correlated metal - but
which remains paramagnetic ... | 1007.5013v2 |
2010-08-01 | Effect of Disorder on Fermi surface in Heavy Electron Systems | The Kondo lattice model with substitutional disorder is studied with
attention to the size of the Fermi surface and the associated Dingle
temperature. The model serves for understanding heavy-fermion Ce compounds
alloyed with La according to substitution Ce{x}La{1-x}. The Fermi surface is
identified from the steepest c... | 1008.0159v1 |
2010-08-06 | Stable fractional flux vortices and unconventional magnetic state in two-component superconductors | In the framework of London theory we study the novel magnetic state in
two-component superconductors with finite density of fractional flux vortices
stabilized near the surface. We show that the process of vortex entry into the
two-component superconductor consists of several steps, while the external
magnetic field in... | 1008.1194v2 |
2010-08-09 | Detection of bottom ferromagnetic electrode oxidation in magnetic tunnel junctions by magnetometry measurements | Surface oxidation of the bottom ferromagnetic (FM) electrode, one of the
major detrimental factors to the performance of a Magnetic Tunnel Junction
(MTJ), is difficult to avoid during the fabrication process of the MTJ's tunnel
barrier. Since Co rich alloys are commonly used for the FM electrodes in MTJs,
over-oxidatio... | 1008.1493v1 |
2010-08-12 | Topological insulators and superconductors | Topological insulators are new states of quantum matter which can not be
adiabatically connected to conventional insulators and semiconductors. They are
characterized by a full insulating gap in the bulk and gapless edge or surface
states which are protected by time-reversal symmetry. These topological
materials have b... | 1008.2026v1 |
2010-08-13 | Dynamics in binary cluster crystals | As a result of the application of coarse-graining procedures to describe
complex fluids, the study of systems consisting of particles interacting
through bounded, repulsive pair potentials has become of increasing interest in
the last years. A well known example is the so-called Generalized Exponential
Model (GEM-$m$),... | 1008.2303v1 |
2010-09-02 | Are there stable long-range ordered Fe(1-x)Cr(x) compounds? | The heat of formation of Fe-Cr alloys undergoes an anomalous change of sign
at small Cr concentrations. This observation raises the question whether there
are intermetallic phases present in this composition range. Here we report the
discovery of several long-range ordered structures that represent ground state
phases ... | 1009.0510v1 |
2010-09-07 | Direct and Inverse Magnetocaloric effects in A-site ordered PrBaMn2O6 manganite in low magnetic fields | The magnetocaloric effect (MCE) of A-site ordered PrBaMn2O6 manganite has
been studied by direct methods and by the specific heat measurements. Direct
measurements of the MCE in low magnetic fields were performed using recently
proposed modulation technique and by classic direct method in high fields.
Direct and invers... | 1009.1228v1 |
2010-09-10 | Permalloy-based carbon nanotube spin-valve | In this Letter we demonstrate that Permalloy (Py), a widely used Ni/Fe alloy,
forms contacts to carbon nanotubes (CNTs) that meet the requirements for the
injection and detection of spin-polarized currents in carbon-based spintronic
devices. We establish the material quality and magnetization properties of Py
strips in... | 1009.1960v1 |
2010-09-12 | Fermi surface of an important nano-sized metastable phase: Al$_3$Li | Nanoscale particles embedded in a metallic matrix are of considerable
interest as a route towards identifying and tailoring material properties. We
present a detailed investigation of the electronic structure, and in particular
the Fermi surface, of a nanoscale phase ($L1_2$ Al$_3$Li) that has so far been
inaccessible ... | 1009.2265v1 |
2010-09-21 | Spectral Properties of Grain Boundaries at Small Angles of Rotation | We study some spectral properties of a simple two-dimensional model for small
angle defects in crystals and alloys. Starting from a periodic potential $V
\colon \R^2 \to \R$, we let $V_\theta(x,y) = V(x,y)$ in the right half-plane
$\{x \ge 0\}$ and $V_\theta = V \circ M_{-\theta}$ in the left half-plane $\{x
< 0\}$, wh... | 1009.4039v2 |
2010-09-24 | Electron concentration effects on the Shastry-Sutherland phase stability in Ce_{2-x}Pd_{2+y}In_{1-z} solid solutions | The stability of a Shastry-Sutherland ShSu phase as a function of electron
concentration is investigated through the field dependence of thermal and
magnetic properties of the solid solution Ce_{2-x}Pd_{2+y}In_{1-z} in the
antiferromagnetic branch. In these alloys the electronic (holes) variation is
realized by increas... | 1009.4840v2 |
2010-09-24 | Far-From-Equilibrium Physics: An Overview | Isolated systems tend to evolve towards equilibrium, a special state that has
been the focus of many-body research for a century. Yet much of the richness of
the world around us arises from conditions far from equilibrium. Phenomena such
as turbulence, earthquakes, fracture, and life itself occur only far from
equilibr... | 1009.4874v1 |
2010-10-03 | Cation-ordering effects in the single layered manganite La(2/3)Sr(4/3)MnO4 | We have synthesized epitaxial La(1-x)Sr(1+x)MnO4 (x=1/3) films as random
alloys and cation-ordered analogues to probe how cation order affects the
properties of a 2D manganite. The films show weak ferromagnetic ordering up to
130 K, although there is a dramatic difference in magnetic anisotropy depending
on the cation ... | 1010.0372v2 |
2010-10-06 | Polymorphic nanowires of magnetic shape memory MnAs | For nanostructured materials, strain is of fundamental importance in
stabilizing a specific crystallographic phase, modifying electronic properties,
and in consequence their magnetism when it applies. Here we describe a magnetic
shape memory alloy in which nanostructure confinement strain influences the
crystallographi... | 1010.1110v1 |
2010-10-09 | Professor C. N. Yang and Statistical Mechanics | Professor Chen Ning Yang has made seminal and influential contributions in
many different areas in theoretical physics. This talk focuses on his
contributions in statistical mechanics, a field in which Professor Yang has
held a continual interest for over sixty years. His Master's thesis was on a
theory of binary alloy... | 1010.1838v1 |
2010-10-12 | Site Occupancy and Lattice Parameters in Sigma-Phase Co-Cr alloys | Neutron diffraction technique was used to study distribution of Co and Cr
atoms over different lattice sites as well as lattice paramaters in sigma-phase
Co100-xCrx compounds with x = 57.0, 62.7 and 65.8. From the diffractograms
recorded in the temperature range of 4.2 - 300 K it was found that all five
sites A, B, C, ... | 1010.2373v1 |
2010-10-25 | Diffusion thermopower of a $p-$type Si/Si$_{1-x}$Ge$_x$ heterostructure at zero magnetic field | We calculate the diffusion thermopower of the degenerate two-dimensional hole
gas in a $p-$type Si/Si$_{1-x}$Ge$_x$ lattice mismatched heterostructure at low
temperatures and zero magnetic field. The effects of possible scatterings, e.g.
remote impurity, alloy disorder, interface roughness, deformation potential,
and r... | 1010.5162v1 |
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