publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
|---|---|---|---|
2013-04-10 | Large room-temperature magnetoresistance in lateral organic spin valves fabricated by in-situ shadow evaporation | We report the successful fabrication of lateral organic spin valves with a
channel length in the sub $100\,nm$ regime. The fabication process is based on
in-situ shadow evaporation under UHV conditions and therefore yields clean and
oxygen-free interfaces between the ferromagnetic metallic electrodes and the
organic se... | 1304.2911v2 |
2013-04-10 | Finite temperature and pressure molecular dynamics for BaFe2As2 | We study the temperature and pressure dependence of the structural and
electronic properties of the iron pnictide superconductor BaFe2As2. We use
density functional theory based Born-Oppenheimer molecular dynamics simulations
to investigate the system at temperatures from T=5 K to 150 K and pressures
from P=0 GPa to 30... | 1304.3039v1 |
2013-04-12 | Effect of Vacuum Annealing on Superconductivity in Fe(Se,Te) Single Crystals | The effect of vacuum annealing on superconductivity is investigated in
Fe(Se,Te) single crystals. It is found that superconductivity is not enhanced
by annealing under high vacuum (~ 10^(-3) Pa) or by annealing in a sealed
evacuated quartz tube. In a moderate vacuum atmosphere (~ 1 Pa), iron oxide
layers are found to s... | 1304.3590v1 |
2013-04-14 | Peculiarities of performance of the spin valve for the superconducting current | The spin valve effect for the superconducting current based on the
superconductor/ferromagnet proximity effect has been studied for a
CoO_x/Fe1/Cu/Fe2/Cu/Pb multilayer. The magnitude of the effect $\Delta T_c$ =
T_c^{AP} - T_c^{P}, where T_c^{P} and T_c^{AP} are the superconducting
transition temperatures for the paral... | 1304.3939v1 |
2013-04-23 | Low-energy bound states at interfaces between superconducting and block antiferromagnet regions in KxFe{2-y}Se2 | The high-Tc alkali doped iron selenide superconductors KxFe{2-y}Se2 have been
recently shown to be intrinsically phase separated into Fe vacancy ordered
block antiferromagnetic regions and superconducting regions at low
temperatures. In this work, we use a microscopic five orbital Hubbard model to
obtain the electronic... | 1304.6424v1 |
2013-04-24 | Thermodynamic Observation of a Vortex Melting Transition in the Fe-based Superconductor Ba0.5K0.5Fe2As2 | In cuprate high-temperature superconductors the small coherence lengths and
high transition termperatures result in strong thermal fluctuations, which
render the superconducting transition in applied magnetic fields into a wide
continuous crossover. A state with zero resistance is found only below the
vortex melting tr... | 1304.6464v1 |
2013-04-26 | Direct microscopic calculations of nuclear level densities in the shell model Monte Carlo approach | Nuclear level densities are crucial for estimating statistical nuclear
reaction rates. The shell model Monte Carlo method is a powerful approach for
microscopic calculation of state densities in very large model spaces. However,
these state densities include the spin degeneracy of each energy level, whereas
experiments... | 1304.7258v1 |
2013-04-28 | Temperature dependent local atomic displacements in Ru substituted SmFe_{1-x}Ru_{x}AsO_{0.85}F_{0.15} superconductors | Local structure of SmFe$_{1-x}$Ru$_x$AsO$_{0.85}$F$_{0.15}$ ($x$ = 0.0, 0.05,
0.25 and 0.5) superconductors has been investigated by temperature dependent As
$K$-edge extended x-ray absorption fine structure. The effect of Ru
substitution remains confined to the iron-arsenide layer but neither the static
disorder nor t... | 1304.7416v1 |
2013-05-01 | Nanotube caps on Ni, Fe, and NiFe nano particles: A path to chirality selective growth | Carbon nanotubes have properties depending on the arrangement of carbon atoms
on the tube walls, called chirality. Also it has been tried to grow nanotubes
of only one chirality for more than a decade it is still not possible today. A
narrowing of the distribution of chiralities, however, which is a first step
towards ... | 1305.0145v1 |
2013-05-06 | Dzyaloshinsky-Moriya driven helical-butterfly structure in Ba3NbFe3Si2O14 | We have used soft x-ray magnetic diffraction at the Fe3+ L2,3 edges to
examine to what extent the Dzyaloshinsky-Moriya interaction in Ba3NbFe3Si2O14
influences its low temperature magnetic structure. A modulated component of the
moments along the c-axis is present, adding to the previously proposed helical
magnetic con... | 1305.1160v1 |
2013-05-06 | Analysis of a carbon dimer bound to a vacancy in iron using density functional theory and a new tight binding model | Recent density functional theory (DFT) calculations by Foerst et al. have
predicted that vacancies in both low and high carbon steels have a carbon dimer
bound to them. This is likely to change the thinking of metallurgists in the
kinetics of the development of microstructures. While the notion of a C2
molecule bound t... | 1305.1171v1 |
2013-05-08 | Nematic State of the Pnictides Stabilized by the Interplay Between Spin, Orbital, and Lattice Degrees of Freedom | The nematic state of the iron-based superconductors is studied in the undoped
limit of the three-orbital ($xz$, $yz$, $xy$) spin-fermion model via the
introduction of lattice degrees of freedom. Monte Carlo simulations show that
in order to stabilize the experimentally observed lattice distortion and
nematic order, and... | 1305.1879v1 |
2013-05-10 | Theory of superconductivity in a three-orbital model of Sr$_2$RuO$_4$ | In conventional and high transition temperature copper oxide and iron
pnictide superconductors, the Cooper pairs all have even parity. As a rare
exception, Sr$_2$RuO$_4$ is the first prime candidate for topological chiral
p-wave superconductivity, which has time-reversal breaking odd-parity Cooper
pairs known to exist ... | 1305.2317v2 |
2013-05-10 | Implementation of non-equilibrium vertex corrections in KKR: transport through disordered layers | The theoretical description of modern nanoelectronic devices requires a
quantum mechanical treatment and often involves disorder, e.g. form alloys.
Therefore, the ab initio theory of transport using non-equilibrium Green's
functions is extended to the case of disorder described by the coherent
potential approximation. ... | 1305.2399v1 |
2013-05-14 | Spectral matching for abundances of 848 stars of the giant branches of the globular cluster ω Centauri | We present the effective temperatures, surface gravities and abundances of
iron, carbon and barium of 848 giant branch stars, of which 557 also have
well-defined nitrogen abundances, of the globular cluster {\omega} Centauri.
This work used photometric sources and lower resolution spectra for this
abundance analysis. S... | 1305.3059v2 |
2013-05-15 | Design and Performance Analysis of a 2.5 MW-Class HTS Synchronous Motor for Ship Propulsion | The development of cryogenic technology and high temperature superconducting
(HTS) materials has seen continued interest worldwide in the development of HTS
machines since the late 1980s. In this paper, the authors present a conceptual
design of a 2.5 MW class synchronous motor. The structure of the motor is
specified ... | 1305.3590v3 |
2013-05-18 | Estimation of Lateral Distribution Function in Extensive Air Showers by Using AIRES Simulation System | In this work the estimation of the lateral distribution function in Extensive
Air showers was performed by using a system for air shower simulations which is
called AIRES version 2.6 for different hadronic models like (QGSJET99, SIBYLL
and SIBYLL1.6). The simulation was fulfilled in the high energy range
(10^15-10^19 e... | 1305.4628v2 |
2013-05-30 | Guided self-assembly of magnetic beads for biomedical applications | Micromagnetic beads are widely used in biomedical applications for cell
separation, drug delivery, and hypothermia cancer treatment. Here we propose to
use self-organized magnetic bead structures which accumulate on fixed magnetic
seeding points to isolate circulating tumor cells. The analysis of circulating
tumor cell... | 1305.7072v1 |
2013-06-03 | Review on Superconducting Materials | Short review of the topical comprehension of the superconductor materials
classes Cuprate High-Temperature Superconductors, other oxide superconductors,
Iron-based Superconductors, Heavy-Fermion Superconductors, Nitride
Superconductors, Organic and other Carbon-based Superconductors and Boride and
Borocarbide Supercond... | 1306.0429v2 |
2013-06-05 | Magnetic chains: From self-buckling to self-assembly | Spherical neodymium-iron-boron magnets are perman-ent magnets that can be
assembled into a variety of structures due to their high magnetic strength. A
one-dimensional chain of these magnets responds to mechanical loadings in a
manner reminiscent of an elastic rod. We investigate the macroscopic mechanical
properties o... | 1306.1014v2 |
2013-06-07 | Negative Magnetoresistance and Spin Filtering of Spin-Coupled Diiron-Oxo Clusters | Spin dependent transport has been investigated for an {\it open shell
singlet} diiron-oxo cluster. Currents and magnetoresistances have been studied,
as a function of spin state, within the non-equilibrium Green's function
approach. The applied bias can be used for tuning the sign of the observed
magnetoresistance. A c... | 1306.1588v2 |
2013-06-07 | Free energy generalization of the Peierls potential in iron | In body-centered cubic (bcc) crystals, ${1}{2}111$ screw dislocations exhibit
high intrinsic lattice friction as a consequence of their non-planar core
structure, which results in a periodic energy landscape known as the Peierls
potential, $U_P$. The main features determining plastic flow, including its
stress and temp... | 1306.1633v4 |
2013-06-11 | Discovery of high-frequency iron K lags in Ark 564 and Mrk 335 | We use archival XMM-Newton observations of Ark 564 and Mrk 335 to calculate
the frequency dependent time-lags for these two well-studied sources. We
discover high-frequency Fe K lags in both sources, indicating that the red wing
of the line precedes the rest frame energy by roughly 100 s and 150 s for Ark
564 and Mrk 3... | 1306.2551v1 |
2013-06-11 | Effect of pressure cycling on Iron: Signatures of an electronic instability and unconventional superconductivity | High pressure electrical resistivity and x-ray diffraction experiments have
been performed on Fe single crystals. The crystallographic investigation
provides direct evidence that in the martensitic $bcc \rightarrow hcp$
transition at 14 GPa the $\lbrace 110\rbrace_{bcc}$ become the $\lbrace
002\rbrace_{hcp}$ directions... | 1306.2587v1 |
2013-06-11 | Nature of the bad metallic behavior of Fe_{1.06}Te inferred from its evolution in the magnetic state | We investigate with angle resolved photoelectron spectroscopy the change of
the Fermi Surface (FS) and the main bands from the paramagnetic (PM) state to
the antiferromagnetic (AFM) occurring below 72 K in Fe_{1.06}Te. The evolution
is completely different from that observed in iron-pnictides as nesting is
absent. The ... | 1306.2603v2 |
2013-06-12 | Hybrid deterministic/stochastic algorithm for large sets of rate equations | We propose a hybrid algorithm for the time integration of large sets of rate
equations coupled by a relatively small number of degrees of freedom. A subset
containing fast degrees of freedom evolves deterministically, while the rest of
the variables evolves stochastically. The emphasis is put on the coupling
between th... | 1306.2817v1 |
2013-06-18 | Of Substitution and Doping: Spatial and Electronic Structure in Fe Pnictides | A highly intriguing aspect in iron-pnictide superconductors is the
composition-dependent electronic structure, in particular the question if and
how charge carriers are introduced to the system upon substitution of Ba by
alkali metals or of Fe by other transition metals, TM. We report on a
systematic study of spatial s... | 1306.4222v2 |
2013-06-18 | Electronic Raman scattering from orbital nematic fluctuations | We compute Raman scattering intensities via the lowest-order coupling to the
bosonic propagator associated with orbital nematic fluctuations in a minimal
model for iron pnictides. The model consists of two bands on a square lattice
exhibiting four Fermi pockets and a transition from the normal to a nematic
state. It is... | 1306.4267v1 |
2013-06-18 | Complex state induced by impurities in multiband superconductors | We study the role of impurities in a two-band superconductor, and elucidate
the nature of the recently predicted transition from s_{+-} state to s_{++}
state induced by interband impurity scattering. Using a Ginzburg-Landau theory,
derived from microscopic equations, we demonstrate that close to T_c this
transition is ... | 1306.4268v2 |
2013-06-18 | Interplay of the electronic and lattice degrees of freedom in A_{1-x}Fe_{2-y}Se_{2} superconductors under pressure | The local structure and electronic properties of Rb$_{1-x}$Fe$_{2-y}$Se$_2$
are investigated by means of site selective polarized x-ray absorption
spectroscopy at the iron and selenium K-edges as a function of pressure. A
combination of dispersive geometry and novel nanodiamond anvil pressure-cell
has permitted to reve... | 1306.4305v1 |
2013-06-18 | Measurement of the elastoresistivity coefficients of the underdoped iron-arsenide Ba(Fe$_{0.975}$Co$_{0.025}$)$_2$As$_2$ | A new method is presented for measuring terms in the elastoresistivity tensor
$m_{ij}$ of single crystal samples with tetragonal symmetry. The technique is
applied to a representative underdoped Fe-arsenide,
Ba(Fe$_{0.975}$Co$_{0.025}$)$_2$As$_2$, revealing an anomalously large and
anisotropic elastoresistance in compa... | 1306.4377v2 |
2013-06-20 | Chiral properties of hematite (α-Fe2O3) inferred from resonant Bragg diffraction using circularly polarized x-rays | Chiral properties of the two phases - collinear motif (below Morin transition
temperature, TM=250 K) and canted motif (above TM) - of magnetically ordered
hematite ({\alpha}-Fe2O3) have been identified in single crystal resonant x-ray
Bragg diffraction, using circular polarized incident x-rays tuned near the iron
K-edg... | 1306.4923v1 |
2013-06-24 | Pseudogap Formation and Quantum Phase Transition in Strongly-Correlated Electron Systems | Pseudogap formation is an ubiquitous phenomena in strongly-correlated
superconductors, for example cuprates, heavy-fermion superconductors, and iron
pnictides. As the system is cooled, an energy gap opens in the excitation
spectrum before entering the superconducting phase. The origin of formation and
the relevancy to ... | 1306.5498v4 |
2013-06-25 | Orbital-Selective Mottness in KxFe2-ySe2 Superconductors Revealed by Pump-Probe Spectroscopy | We report transient optical signatures of the orbital-selective Mottness in
superconducting KxFe2-ySe2 crystals by using dual-color pump-probe
spectroscopy. Besides multi-exponential decay recovery dynamics of
photo-induced quasiparticles, a damped oscillatory component due to coherent
acoustic phonons emerges when the... | 1306.5817v1 |
2013-06-25 | Collision-Induced Dissociation Studies on Fe(O2)n+ (n=1-6) Clusters: Application of a New Technique Based on Crossed Molecular Beams | Gas-phase oxygen-rich iron oxide clusters Fe(O2)n+ (n=1-6), are produced in a
molecular beam apparatus. Their stability and structure are investigated by
measuring the fragmentation cross sections from collision-induced-dissociation
experiments. For this purpose, two different techniques have been employed. The
first o... | 1306.5902v1 |
2013-06-25 | The influence of oxygen and hydrogen adsorption on the magnetic structure of the ultrathin iron film on the Ir(001) surface | We present a detailed ab initio study of the electronic structure and
magnetic order of an Fe monolayer on the Ir(001) surface covered by adsorbed
oxygen and hydrogen. The results are compared to the clean Fe/Ir(001) system,
where recent intensive studies indicated a strong tendency towards an
antiferromagnetic order a... | 1306.5925v1 |
2013-06-25 | The Effect of Hydrogen Adsorption on the Magnetic Properties of a Surface Nanocluster of Iron | The effect of hydrogen adsorption on the magnetic properties of an Fe$_3$
cluster immersed in a Cu(111) surface has been calculated using densifty
functional theory and the results used to parametrize an Alexander-Anderson
model which takes into account the interaction of d-electrons with itinerant
electrons. A number ... | 1306.5999v1 |
2013-07-04 | Prediction of phonon-mediated high temperature superconductivity in stoichiometric Li$_2$B$_3$C | The discovery of superconductivity in Magnesium Diborate (MgB$_2$) has
stimulated great interest in the search of new superconductors with similar
lattice structures. Unlike cuprate or iron-based superconductors, MgB$_2$ is
indisputably a phonon-mediated high temperature superconductor. The emergence
of high temperatur... | 1307.1323v1 |
2013-07-04 | "Anti-glitches" in the Quark-Nova model for AXPs | In the Quark-Nova model, AXPs are quark stars surrounded by a degenerate
iron-rich Keplerian ring (a few stellar radii away). AXP bursts are caused by
accretion of chunks from the inner edge of the ring following magnetic field
penetration. For bright bursts, the inner disk is prone to radiation induced
warping which c... | 1307.1386v2 |
2013-07-07 | Andreev Reflection Like Enhancement Above Bulk $T_c$ in Electron Underdoped Iron Arsenides | We use point contact spectroscopy (PCS) to probe the superconducting
properties of electron doped $\rm{Ba(Fe_{1-x}Co_x)_2As_2}$ ($\rm{x = 0.05,
0.055, 0.07, 0.08}$) and hole doped $\rm{Ba_{0.8}K_{0.2}Fe_2As_2}$. PCS
directly probes the low energy density of states via Andreev reflection,
revealing two distinct supercon... | 1307.1908v1 |
2013-07-10 | Kondo-like mass enhancement of Dirac fermion in iron pnictides Ba(Fe$_{1-x}$Mn$_x$As)$_2$ | The effect of Mn substitution, acting as a magnetic impurity for Fe, on the
Dirac cone was investigated in Ba(Fe$_{1-x}$Mn$_x$As)$_2$. Both
magnetoresistance and Hall resistivity studies clearly indicate that the
cyclotron effective mass ($m^{\ast}$) of the Dirac cone is anomalously enhanced
at low temperatures by the ... | 1307.2813v3 |
2013-07-11 | Progressive slowing down of spin fluctuations in underdoped LaFeAsO$_{1-x}$F$_x$ | The evolution of low-energy spin dynamics in the iron-based superconductor
LaFeAsO$_{1-x}$F$_x$ was studied over a broad doping, temperature, and magnetic
field range (x = 0 - 0.15, T up to 480K, H up to 30T) by means of As nuclear
magnetic resonance (NMR). An enhanced spin-lattice relaxation rate divided by
temperatur... | 1307.3138v1 |
2013-07-12 | $B_{1g}$-like pairing states in two-leg ladder iron superconductors | Motivated by the recent report of superconductivity in Fe-based ladder
materials, we study the pairing state of a multi-orbital t-J model defined on
two-leg ladders using the standard mean-field theory. We find that the
superconducting order parameters change sign between the $d_{xz}$ and $d_{yz}$
orbitals in most of t... | 1307.3309v2 |
2013-07-12 | Electron-capture supernovae as sources of 60Fe | We investigate the nucleosynthesis of the radionuclide 60Fe in
electron-capture supernovae (ECSNe). The nucleosynthetic results are based on a
self-consistent, two-dimensional simulation of an ECSN as well as models in
which the densities are systematically increased by some factors (low-entropy
models). 60Fe is found ... | 1307.3319v2 |
2013-07-12 | Electronic effects in high-energy radiation damage in iron | Electronic effects are believed to be important in high--energy radiation
damage processes where high electronic temperature is expected, yet their
effects are not currently understood. Here, we perform molecular dynamics
simulations of high-energy collision cascades in $\alpha$-iron using the
coupled two-temperature m... | 1307.3385v2 |
2013-07-12 | Artificially engineered superlattices of pnictide superconductor | Significant progress has been achieved in fabricating high quality bulk and
thinfilm iron-based superconductors. In particular, artificial layered pnictide
superlattices offer the possibility of tailoring the superconducting properties
and understanding the mechanism of the superconductivity itself. For high field
appl... | 1307.3576v1 |
2013-07-17 | Growth modes of nanoparticle superlattice thin films | We report about the fabrication and characterization of iron oxide
nanoparticle thin film superlattices. The formation into different film
morphologies is controlled by tuning the particle plus solvent-to-substrate
interaction. It turns out that the wetting vs. dewetting properties of the
solvent before the self-assemb... | 1307.4693v4 |
2013-07-19 | Microstructure and Structural Phase Transitions in Iron-Based Superconductors | Crystal structures and microstructural features, such as structural phase
transitions, defect structures, chemical and structural inhomogeneities, are
known to have profound effects on the physical properties of superconducting
materials. Recently, a large amount of works on the structural properties of
Fe-based high-T... | 1307.5112v1 |
2013-07-24 | Role of Dirac cones in magnetotransport properties of REFeAsO (RE=rare earth) oxypnictides | In this work we study the effect of the rare earth element in iron
oxypnictides of composition REFeAsO (RE=rare earth). On one hand we carry out
Density Functional Theory calculations of the band structure, which evidence
the multiband character of these compounds and the presence of Dirac cones
along the Y-{\Gamma} an... | 1307.6352v1 |
2013-07-26 | N-Body Simulation of the Formation of the Earth-Moon System from a Single Giant Impact | The giant impact hypothesis is the dominant theory of how the Earth-Moon
system was formed. Models have been created that can produce a disk of debris
with the proper mass and composition to create our Moon. Models have also been
created which start with a disk of debris that eventually coalesces into a
Moon. To date, ... | 1307.7062v1 |
2013-07-26 | Ferro-orbital ordering transition in iron telluride Fe$_{1+y}$Te | Fe$_{1+y}$Te with $y \lesssim 0.05$ exhibits a first-order phase transition
on cooling to a state with a lowered structural symmetry, bicollinear
antiferromagnetic order, and metallic conductivity, $d\rho/dT > 0$. Here, we
study samples with $y = 0.09(1)$, where the frustration effects of the
interstitial Fe decouple d... | 1307.7162v2 |
2013-07-26 | Linear magnetoconductivity in multiband spin-density-wave metals with nonideal nesting | In several parent iron-pnictide compounds the resistivity has an extended
range of linear magnetic field dependence. We argue that there is a simple and
natural explanation of this behavior. Spin density wave transition leads to
Fermi-surface reconstruction corresponding to strong modification of the
electronic spectru... | 1307.7184v3 |
2013-07-29 | Simple concentration-dependent pair interaction model for large-scale simulations of Fe-Cr alloys | This work is motivated by the need for large-scale simulations to extract
physical information on the iron-chromium system that is a binary model alloy
for ferritic steels used or proposed in many nuclear applications. From
first-principles calculations and the experimental critical temperature we
build a new energetic... | 1307.7561v1 |
2013-08-02 | Effect of heavy-ion irradiation on London penetration depth in over-doped Ba(Fe,Co)2As2 | Irradiation with 1.4 GeV $^{208}$Pb ions was used to induce artificial
disorder in single crystals of iron-arsenide superconductor
Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ and to study its effect on the
temperature-dependent London penetration depth and transport properties. Study
was undertaken on overdoped single crystals with... | 1308.0537v1 |
2013-08-10 | Impurity effects on electronic transport in ferropnictide superconductors | Effects of impurities and disorder on transport properties by electronic
quasiparticles in superconducting iron pnictides are theoretically considered.
The most prominent new features compared to the case of pure material should
appear at high enough impurity concentration when a specific narrow band of
conducting quas... | 1308.2351v3 |
2013-08-13 | Strain effects on the electronic structure of the FeSe0.5Te0.5 superconductor | The electronic structure of the strained FeSe0.5Te0.5 superconductor has been
investigated from first principles. Our calculation results indicate that the
influence of hydrostatic, biaxial or uniaxial compressive stress on the density
of states at the Fermi level is insignificant. The overall shape of the
Fermi-surfac... | 1308.2949v1 |
2013-08-15 | Magnetic Phase Diagram of a Five-Orbital Hubbard Model in the Real-Space Hartree Fock Approximation Varying the Electronic Density | Using the real-space Hartree Fock approximation, the magnetic phase diagram
of a five-orbital Hubbard model for the iron-based superconductors is studied
varying the electronic density $n$ in the range from 5 to 7 electrons per
transition metal atom. The Hubbard interaction $U$ is also varied, at a fixed
Hund coupling ... | 1308.3426v1 |
2013-08-16 | Quantum Criticality in Electron-doped BaFe_{2-x}Ni_xAs_2 | A quantum critical point (QCP) is a point in a system's phase diagram at
which an order is completely suppressed at absolute zero temperature (T). The
presence of a quantum critical point manifests itself in the finite-T physical
properties, and often gives rise to new states of matter. Superconductivity in
the cuprate... | 1308.3539v1 |
2013-08-18 | Spin excitation anisotropy as a probe of orbital ordering in the paramagnetic tetragonal phase of superconducting BaFe1.904Ni0.096As2 | We use polarized neutron scattering to demonstrate that in-plane spin
excitations in electron doped superconducting BaFe1.904Ni0.096As2 (Tc=19.8 K)
change from isotropic to anisotropic in the tetragonal phase well above the
antiferromagnetic (AF) ordering and tetragonal-to-orthorhombic lattice
distortion temperatures (... | 1308.3858v1 |
2013-08-19 | The Origin of HVS17, an Unbound Main Sequence B Star at 50 kpc | We analyze Keck ESI spectroscopy of HVS17, a B-type star traveling with a
Galactic rest frame radial velocity of +445 km/s in the outer halo of the Milky
Way. HVS17 has the projected rotation of a main sequence B star and is
chemically peculiar, with solar iron abundance and sub-solar alpha abundance.
Comparing measure... | 1308.4181v1 |
2013-08-20 | Spatial Inhomogeneity of the Superconducting Gap and Order Parameter in FeSe_{0.4}Te_{0.6} | We have performed a low temperature scanning tunneling microscopy and
spectroscopy study of the iron chalcogenide superconductor FeSe_{0.4}Te_{0.6}
with T_{C}~14 K. Spatially resolved measurements of the superconducting gap
reveal substantial inhomogeneity on a nanometer length scale. Analysis of the
structure of the g... | 1308.4339v1 |
2013-08-22 | A Precision Measurement of Charm Dimuon Production in Neutrino Interactions from the NOMAD Experiment | We present our new measurement of the cross-section for charm dimuon
production in neutrino-iron interactions based upon the full statistics
collected by the NOMAD experiment. After background subtraction we observe
15,344 charm dimuon events, providing the largest sample currently available.
The analysis exploits the ... | 1308.4750v1 |
2013-08-27 | Origin of Dust around V1309 Sco | The origin of dust grains in the interstellar medium is still open problem.
\cite{Nicholls2013} found the presence of a significant amount of dust around
V1309 Sco which maybe originate from the merger of a contact binary. We
investigate the origin of dust around V1309 Sco, and suggest that these dust
grains are effici... | 1308.5735v1 |
2013-08-27 | Calculating Time Lags From Unevenly-Sampled Light Curves | Timing techniques offer powerful tools to study dynamical astrophysical
phenomena. In the X-ray band, they offer the potential of probing accretion
physics down to the event horizon. Recent work has used frequency and
energy-dependent time lags as a tool for studying relativistic reverberation
around the black holes in... | 1308.5852v1 |
2013-08-28 | Tunneling spectroscopy for probing orbital anisotropy in iron pnictides | Using realistic multi-orbital tight-binding Hamiltonians and the T-matrix
formalism, we explore the effects of a non-magnetic impurity on the local
density of states in Fe-based compounds. We show that scanning tunneling
spectroscopy (STS) has very specific anisotropic signatures that track the
evolution of orbital spl... | 1308.6248v2 |
2013-08-30 | Why is the superconducting Tc so high in rare-earth-doped CaFe2As2? | In rare-earth doped single crystalline CaFe2As2, the mysterious small volume
fraction which superconducts up to 49 K, much higher than the bulk Tc ~ 30s K,
has prompted a long search for a hidden variable that could enhance the Tc by
more than 30% in iron-based superconductors of the same structure. Here we
report a ch... | 1309.0034v2 |
2013-09-08 | Evidence of unconventional low-frequency dynamics in the normal phase of Ba(Fe1-xRhx)2As2 iron-based supercondutors | This work presents 75As NMR spin echo decay rate (1/T2) measurements in
Ba(Fe1-xRhx)2As2 superconductors, for 0.041 < x < 0.094. It is shown that 1/T2
increases upon cooling, in the normal phase, suggesting the onset of an
unconventional very low-frequency activated dynamic. The correlation times of
the fluctuations an... | 1309.1936v1 |
2013-09-11 | Concepts relating magnetic interactions, intertwined electronic orders and strongly correlated superconductivity | Unconventional superconductivity (SC) is said to occur when Cooper pair
formation is dominated by repulsive electron-electron interactions, so that the
symmetry of the pair wavefunction is other than isotropic s-wave. The strong,
on-site, repulsive electron-electron interactions that are the proximate cause
of such sup... | 1309.2719v1 |
2013-09-12 | Low-energy interband transitions in the infrared response of Ba(Fe1-xCox)2As2 | We studied the doping and temperature (T) dependence of the infrared (IR)
response of Ba(Fe1-xCox)2As2 single crystals. We show that a weak band around
1000 cm-1, that was previously interpreted in terms of interaction of the
charge carriers with magnetic excitations or of a pseudogap, is rather related
to low-energy i... | 1309.3198v1 |
2013-09-13 | The lateral shower age parameter as an estimator of chemical composition | We explore the feasibility of estimating primary cosmic ray composition at
ultra high energies from the study of lateral age parameter of Extensive Air
Showers (EAS) at ground level. Using different types of lateral distribution
functions, we fit the particle density of simulated EAS to find the lateral age
parameter. ... | 1309.3536v1 |
2013-09-17 | Strongly Correlated Materials | Strongly correlated materials are profoundly affected by the repulsive
electron-electron interaction. This stands in contrast to many commonly used
materials such as silicon and aluminum, whose properties are comparatively
unaffected by the Coulomb repulsion. Correlated materials often have remarkable
properties and tr... | 1309.4473v1 |
2013-09-23 | Interactions of Cosmic Rays in the Atmosphere: Growth Curves Revisited | Measurements of cosmic-ray abundances on balloons are affected by
interactions in the residual atmosphere above the balloon. Corrections for such
interactions are particularly important for observations of rare secondary
particles such as boron, antiprotons and positrons. These corrections can
either be calculated if t... | 1309.5739v1 |
2013-09-26 | The polluted atmosphere of the white dwarf NLTT 25792 and the diversity of circumstellar environments | We present an analysis of X-Shooter spectra of the polluted, hydrogen-rich
white dwarf NLTT 25792. The spectra show strong lines of calcium (Ca H&K,
near-infrared calcium triplet, and Ca I 4226 and numerous lines of iron along
with magnesium and aluminum lines from which we draw the abundance pattern.
Moreover, the pho... | 1309.6804v1 |
2013-09-27 | Unusual pressure effects on the superconductivity of indirectly electron-doped (Ba1-xLax)Fe2As2 epitaxial films | Applying an external pressure to indirectly electron-doped 122-type
(Ba1-xLax)Fe2As2 epitaxial films enhances the superconducting critical
temperature (Tc) up to 30.3 K. Different from the other family compounds, the
Tc is enhanced not only in the under-doped region but also in the optimally
doped and over-doped region... | 1309.7100v2 |
2013-09-27 | Beating the superparamagnetic size limit of nanoparticles on a ferroelectric substrate | When decreasing the size of nanoscale magnetic particles their magnetization
becomes vulnerable to thermal fluctuations as approaching the superparamgnetic
limit, hindering thus applications relying on a stable magnetization. Here, we
show theoretically that a magnetoelectric coupling to a ferroelectric substrate
rende... | 1309.7136v1 |
2013-09-27 | Inelastic neutron scattering study of crystal field excitations of Nd3+ in NdFeAsO | Inelastic neutron scattering experiments were performed to investigate the
crystalline electric field (CEF) excitations of Nd3+ (J = 9/2) in the iron
pnictide NdFeAsO. The crystal field level structures for both the
high-temperature paramagnetic phase and the low-temperature antiferromagnetic
phase of NdFeAsO are const... | 1309.7323v1 |
2013-09-29 | Coupled magnetic and ferroelectric excitations in PbFe_{1/2}Nb_{1/2}O_{3} | A neutron scattering investigation of the magnetoelectric coupling in
PbFe_{1/2}Nb_{1/2}O_{3} (PFN) has been undertaken. Ferroelectric order occurs
below 400 K, as evidenced by the softening with temperature and subsequent
recovery of the zone center transverse optic phonon mode energy (\hbar
\Omega_{0}). Over the same... | 1309.7587v1 |
2013-09-29 | Strongly enhanced current densities in Sr0.6K0.4Fe2As2 superconducting tapes | Improving transport current has been the primary issue for practical
application of superconducting wires and tapes. However, the porous nature of
powder-in-tube (PIT) processed iron-based superconducting tapes is thought to
be one of the important reasons for the low Jc values. In this work, the
superconducting core d... | 1309.7618v2 |
2013-10-02 | Chemical Abundances of RR Lyrae Type C Star AS162158 | We report the first extensive model atmosphere and detailed chemical
abundance study of eight RR Lyrae variable stars of c subclass throughout their
pulsation cycles. Atmospheric parameters effective temperature, surface
gravity, microturbulent velocity, and metallicity have been derived. Spectra
for this abundace anal... | 1310.0580v1 |
2013-10-04 | In-plane spin excitation anisotropy in the paramagnetic phase of NaFeAs | We use unpolarized and polarized inelastic neutron scattering to study
low-energy spin excitations in NaFeAs, which exhibits a
tetragonal-to-orthorhombic lattice distortion at $T_s\approx 58$ K followed by
a collinear antiferromagnetic (AF) order below $T_N\approx 45$ K. In the AF
ordered state ($T<T_N$), spin waves ar... | 1310.1143v1 |
2013-10-09 | Spin resonance in AFe2Se2 with s-wave pairing symmetry | We study spin resonance in the superconducting state of recently discovered
alkali-intercalated iron selenide materials A_xFe_(2-y)Se_2 (A=K,Rb,Cs) in
which the Fermi surface has only electron pockets. Recent angle-resolved
photoemission spectroscopy (ARPES) studies [M. Xu et al., Phys. Rev. B 85,
220504(R) (2012)] wer... | 1310.2334v2 |
2013-10-10 | Strange Inter-layer Properties of $Ba(Fe_{1-x}Co_x)2As_2$ Appearing in Ultrasonic Measurements | We have investigated the elastic constant C33 of Ba(Fe1-xCox)2As2 with eight
different Co concentrations by ultrasonic measurement. We found remarkable
elastic anomalies near the quantum critical point. We have studied them by
measuring the electrical resistivity, heat capacity, and ultrasonic attenuation
in addition t... | 1310.2681v1 |
2013-10-11 | Enhanced superconductivity and evidence for novel pairing in single-layer FeSe on SrTiO3 thin film under large tensile strain | Single-layer FeSe films with extremely expanded in-plane lattice constant of
3.99A are fabricated by epitaxially growing FeSe/Nb:SrTiO3/KTaO3
heterostructures, and studied by in situ angle-resolved photoemission
spectroscopy. Two elliptical electron pockets at the Brillion zone corner are
resolved with negligible hybri... | 1310.3060v1 |
2013-10-20 | Impurity effects in Cu$_2$O | The doping of wide gap semiconductors is an interesting problem both from the
scientific and technological point of view. A well known example of this
problem is the doping of Cu$_2$O. The only element which has produced an order
of magnitude increase in the conductivity of Cu$_2$O bulk samples is chlorine,
as previous... | 1310.5341v1 |
2013-10-22 | Point defect modeling in materials: coupling ab initio and elasticity approaches | Modeling point defects at an atomic scale requires careful treatment of the
long-range atomic relaxations. This elastic field can strongly affect point
defect properties calculated in atomistic simulations because of the finite
size of the system under study. This is an important restriction for ab initio
methods which... | 1310.5799v1 |
2013-10-22 | Nucleosynthesis inside accretion disks and outflows formed during core collapse of massive stars | We investigate nucleosynthesis inside the gamma-ray burst (GRB) accretion
disks and in the outflows launched from these disks mainly in the context of
Type II collapsars. We report the synthesis of several unusual nuclei like 31P,
39K, 43Sc, 35Cl and various isotopes of titanium, vanadium, chromium, manganese
and coppe... | 1310.5911v1 |
2013-10-22 | Large low-temperature magnetoresistance in SrFe2As2 single crystals | We present the first report on a large low-temperature magnetoresistance (MR)
of more than 1600% in a SrFe2As2 single crystal and 1300% in a low-energy Ca
ion-implanted SrFe2As2 single crystal that occurs before the emergence of
crystallographic strain-induced bulk superconductivity arising from a sample
aging effect. ... | 1310.6071v1 |
2013-10-28 | Principle of Maximum Entanglement Entropy and Local Physics of Correlated many-body Electron-Systems | We argue that, because of the quantum-entanglement, the local physics of the
strongly-correlated materials at zero temperature is described in very good
approximation by a simple generalized Gibbs distribution, which depends on a
relatively small number local quantum thermodynamical potentials. We
demonstrate that our ... | 1310.7520v2 |
2013-10-28 | Enhanced Superconductivity on the Tetragonal Lattice in FeSe under Hydrostatic Pressure | Superconductivity under pressure in FeSe ($T_{\rm c}$$\sim$7.5 K) has been
investigated using single-crystal specimens through the measurements of DC
magnetization and electrical resistivity. A characteristic three-step increase
in $T_{\rm c}$ has been found under hydrostatic pressure up to $\sim$34 K above
7 GPa. The ... | 1310.7546v3 |
2013-11-01 | New Li-Ethylenediamine-Intercalated Superconductor Li$_x$(C$_2$H$_8$N$_2$)$_y$Fe$_{2-z}$Se$_2$ with $T_c$ = 45 K | A new iron-based superconductor Li$_x$(C$_2$H$_8$N$_2$)$_y$Fe$_{2-z}$Se$_2$
with $T_c$ = 45 K has successfully been synthesized via intercalation of
dissolved lithium metal in ethylenediamine. The distance between neighboring Fe
layers is 10.37 {\AA} and much larger than those of FeSe with $T_c$ = 8 K and
K$_x$Fe$_2$Se... | 1311.0141v1 |
2013-11-03 | s-wave pairing in the optimally-doped LaO0.5F0.5BiS2 superconductor | We report on the magnetic and superconducting properties of LaO0.5F0.5BiS2 by
means of zero- (ZF) and transverse-field (TF) muon-spin spectroscopy
measurements (uSR). Contrary to previous results on iron-based superconductors,
measurements in zero field demonstrate the absence of magnetically ordered
phases. TF-uSR dat... | 1311.0457v2 |
2013-11-03 | Magnetization distribution and orbital moment in the non-Superconducting Chalcogenide Compound K0.8Fe1.6Se2 | We have used polarized and unpolarized neutron diffraction to determine the
spatial distribution of the magnetization density induced by a magnetic field
of 9 T in the tetragonal phase of K0.8Fe1.6Se2. The maximum entropy
reconstruction shows clearly that most of the magnetization is confined to the
region around the i... | 1311.0492v1 |
2013-11-04 | An extended Heitler-Matthews model for the full hadronic cascade in cosmic air showers | The Heitler-Matthews model for hadronic air showers will be extended to all
the generations of electromagnetic subshowers in the hadronic cascade. The
analysis is outlined in detail for showers initiated by primary protons. For
showers initiated by iron primaries the part of the analysis is given for as
far as it diffe... | 1311.0642v3 |
2013-11-06 | On the Sodium versus Iron Correlation in Late B-Type Stars | With an aim to study whether the close correlation between [Na/H] and [Fe/H]
recently found in A-type stars further persists in the regime of B-type stars,
the abundances of Na were determined for 30 selected sharp-lined late B-type
stars (10000K < T_eff < 14000K) from the Na I 5890/5896 doublet. These Na
abundances we... | 1311.1260v1 |
2013-11-06 | Enhanced Superconductivity up to 43 K by P/Sb Doping of Ca1-xLaxFeAs2 | The effects of isovalent doping on the superconducting transition temperature
Tc in novel 112-type iron arsenide Ca1-xLaxFeAs2 were studied by conducting
measurements of electrical resistivity rho and magnetization M. P or Sb doping
strongly enhances Tc: P-doped Ca0.84La0.16FeAs2 and Sb-doped Ca0.85La0.15FeAs2
exhibite... | 1311.1269v2 |
2013-11-06 | Superconductivity in Ca10(Ir4As8)(Fe2As2)5 with Square-Planar Coordination of Iridium | We report the unprecedented square-planar coordination of iridium in the iron
iridium arsenide Ca10(Ir4As8)(Fe2As2)5. This material experiences
superconductivity at 16 K. X-ray photoemission spectroscopy and first-
principles band calculation suggest Ir(II) oxidation state, which yields
electrically conductive Ir4As8 l... | 1311.1280v1 |
2013-11-07 | The Terzan 5 puzzle: discovery of a third, metal-poor component | We report on the discovery of 3 metal-poor giant stars in Terzan 5, a complex
stellar system in the the Galactic bulge, known to have two populations at
[Fe/H]=-0.25 and +0.3. For these 3 stars we present new echelle spectra
obtained with NIRSPEC at Keck II, which confirm their radial velocity
membership and provide av... | 1311.1706v1 |
2013-11-09 | Formation of Nanofoam carbon and re-emergence of Superconductivity in compressed CaC6 | Pressure can tune material's electronic properties and control its quantum
state, making some systems present disconnected superconducting region as
observed in iron chalcogenides and heavy fermion CeCu2Si2. For CaC6
superconductor (Tc of 11.5 K), applying pressure first Tc increases and then
suppresses and the superco... | 1311.2184v2 |
2013-11-12 | Unconventional sign-changing superconductivity near quantum criticality in YFe$_2$Ge$_2$ | I present the results of first principles calculations of the electronic
structure and magnetic interactions for the recently discovered superconductor
YFe$_2$Ge$_2$ and use them to identify the nature of superconductivity and
quantum criticality in this compound. I find that the Fe $3d$ derived states
near the Fermi l... | 1311.2922v1 |
2013-11-20 | Polarization-Dependent Three-Dimensional Angle-Resolved Photoemission Spectroscopy of BaFe$_{1.8}$Co$_{0.2}$As$_{2}$ | We performed polarization- and photon-energy-dependent angle-resolved
photoemission spectroscopy of a slightly overdoped iron pnictide
superconductor, BaFe$_{1.8}$Co$_{0.2}$As$_{2}$, to clarify the
three-dimensional electronic structure including its orbital characters at the
Brillouin zone center. Two hole Fermi surfa... | 1311.4990v1 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.