publicationDate
stringlengths
1
2.79k
title
stringlengths
1
36.5k
abstract
stringlengths
1
37.3k
id
stringlengths
9
47
2014-08-02
Synthesis and post-annealing effects of alkaline-metal-ethylenediamine-intercalated superconductors Ax(C2H8N2)yFe2-zSe2 (A = Li, Na) with Tc = 45 K
New iron-based intercalation superconductors Ax(C2H8N2)yFe2-zSe2 (A = Li, Na) with Tc = 45 K have successfully been synthesized via intercalation of dissolved alkaline metal in ethylenediamine. The c-axis lengths of Ax(C2H8N2)yFe2-zSe2 (A = Li, Na) are 20.74(7) {\AA} and 21.9(1) {\AA}, respectively, and are about 50 % ...
1408.0346v1
2014-08-06
Permanent magnet with MgB2 bulk superconductor
Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging (MRI). The recent global helium shortage has quickened research into high-temperature superconductors (HTSs) materials that can...
1408.1277v1
2014-08-08
Orbital-driven nematicity in FeSe
A very fundamental and unconventional characteristic of superconductivity in iron-based materials is that it occurs in the vicinity of {\it two} other instabilities. Apart from a tendency towards magnetic order, these Fe-based systems have a propensity for nematic ordering: a lowering of the rotational symmetry while t...
1408.1875v3
2014-08-09
Stellar origin of the 182Hf cosmochronometer and the presolar history of solar system matter
Among the short-lived radioactive nuclei inferred to be present in the early solar system via meteoritic analyses, there are several heavier than iron whose stellar origin has been poorly understood. In particular, the abundances inferred for 182Hf (half-life = 8.9 million years) and 129I (half-life = 15.7 million year...
1408.2050v1
2014-08-12
Nematic spin correlations in the tetragonal state of uniaxial strained BaFe2-xNixAs2
Understanding the microscopic origins of electronic phases in high-transition temperature (high-Tc) superconductors is important for elucidating the mechanism of superconductivity. In the paramagnetic tetragonal phase of BaFe2-xTxAs2 (where T is Co or Ni) iron pnictides, an in-plane resistivity anisotropy has been obse...
1408.2756v1
2014-08-13
Dynamical correlations and screened exchange on the experimental bench: spectral properties of the cobalt pnictide BaCo2As2
Understanding the Fermi surface and low-energy excitations of iron or cobalt pnictides is crucial for assessing electronic instabilities such as magnetic or superconducting states. Here, we propose and implement a new approach to compute the low-energy properties of correlated electron materials, taking into account bo...
1408.3136v2
2014-08-14
Role of magnetic degrees of freedom in a scenario of phase transformations in steel
The diversity of mesostructures formed in steel at cooling from a high-temperature austenite ("gamma") phase is determined by the interplay of shear reconstructions of crystal lattice and diffusion of carbon. Combining first-principles calculations with large-scale phase-field simulations we demonstrate a decisive role...
1408.3275v2
2014-08-17
Interaction between multi components vortices at arbitrary distances using a variational method in the Ginzburg-Landau theory
We study the interaction between the vortices in multi components superconductors based on the Jacobs and Rebbi variation method using Ginzburg-Landau theory. With one condensation, we get attraction interaction between the vortices for type I and repulsion for type II superconductors. With two condensation states such...
1408.3834v2
2014-08-19
Anomalous Superconducting-Gap Structure of Slightly Overdoped Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$
We observed the anisotropic superconducting-gap (SC-gap) structure of a slightly overdoped superconductor, Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ ($x=0.1$), using three-dimensional (3D) angle-resolved photoemission spectroscopy. Two hole Fermi surfaces (FSs) observed at the Brillouin zone center and an inner electron FS ...
1408.4260v1
2014-08-25
Ground state, collective mode, phase soliton and vortex in multiband superconductors
This article reviews theoretical and experimental work on the novel physics in multiband superconductors. Multiband superconductors are characterized by multiple superconducting energy gaps in different bands with interaction between Cooper pairs in these bands. The discovery of prominent multiband superconductors $\ma...
1408.5938v2
2014-08-26
Measurement of the Velocity of the Neutrino with MINOS
The MINOS experiment uses a beam of predominantly muon-type neutrinos generated using protons from the Main Injector at Fermilab in Batavia, IL, and travelling 735 km through the Earth to a disused iron mine in Soudan, MN. The 10{\mu}s-long beam pulse contains fine time structure which allows a precise measurement of t...
1408.6267v1
2014-08-29
The spin of the black hole 4U 1543-47
We present a new analysis of Rossi X-ray Timing Explorer observations of the 2002 outburst of the transient X-ray nova 4U 1543-47. We focus on observations in the High/Soft state, and attempt to measure the spin of the black hole by simultaneously fitting the thermal disk continuum and by modeling the broadened iron k-...
1408.7028v1
2014-09-01
Magnetic structure of the Eu2+ moments in superconducting EuFe2(As1-xPx)2 with x = 0.19
The magnetic structure of the Eu2+ moments in the superconducting EuFe2(As1-xPx)2 sample with x = 0.19 has been determined using neutron scattering. We conclude that the Eu2+ moments are aligned along the c direction below T_C = 19.0(1) K with an ordered moment of 6.6(2) mu_B in the superconducting state. An impurity p...
1409.0432v1
2014-09-07
Quantum Monte Carlo study of the $S_4$ symmetric microscopic model for iron-based superconductors
The $S_4$ symmetric microscopic model with two iso-spin components has been studied via constrained-path quantum Monte Carlo simulation. Our results demonstrate a stable $(\pi,0)$ or $(0,\pi)$ magnetic order which is significantly enhanced on increasing both the Coulomb repulsion $U$ and Hund's coupling strength $J$. A...
1409.2075v1
2014-09-08
The sensitivity of the ICAL detector at India-based Neutrino Observatory to neutrino oscillation parameters
The India-based Neutrino Observatory (INO) will host a 50 kt magnetized iron calorimeter (ICAL) detector that will be able to detect muon tracks and hadron showers produced by Charged-Current muon neutrino interactions in the detector. The ICAL experiment will be able to determine the precision of atmospheric neutrino ...
1409.2231v1
2014-09-09
Anomalous density of states in multiband superconductors near Lifshitz transition
We consider a multiband metal with deep primary bands and a shallow secondary one. In the normal state the system undergoes Lifshitz transition when the bottom of the shallow band crosses the Fermi level. In the superconducting state Cooper pairing in the shallow band is induced by the deep ones. As a result, the densi...
1409.2807v2
2014-09-09
The diversity of quasars unified by accretion and orientation
Quasars are rapidly accreting supermassive black holes at the center of massive galaxies. They display a broad range of properties across all wavelengths, reflecting the diversity in the physical conditions of the regions close to the central engine. These properties, however, are not random, but form well-defined tren...
1409.2887v1
2014-09-10
Theoretical investigation of the electronic and magnetic properties of the orthorhombic phase of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$
We present a comprehensive study on the low-temperature orthorhombic phase of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ based on the Korringa-Kohn-Rostoker-Green function approach. Using this bandstructure method in combination with the coherent potential approximation alloy theory we are able to investigate the evolution of the ...
1409.3099v1
2014-09-10
On the Raman O VI and related lines in classical novae
We critically examine the recent claimed detection of Raman scattered O VI at around 6830\AA\ in the iron curtain stage spectra of the classical CO nova V339 Del. The observed line variations are compatible in profile and timing of emission line strength with an excited state transition of neutral carbon. Line formatio...
1409.3240v1
2014-09-11
Effects of applied strain on radiation damage generation in body-centered cubic iron
Radiation damage in body-centered cubic (BCC) Fe has been extensively studied by computer simulations to quantify effects of temperature, impinging particle energy, and the presence of extrinsic particles. However, limited investigation has been conducted into the effects of mechanical stresses and strain. In a reactor...
1409.3519v2
2014-09-13
Coexistence of 3d-ferromagnetism and superconductivity in [(Li(1-x)Fex)OH](Fe(1-y)Liy)Se
Superconducting [(Li(1-x)Fex)OH](Fe(1-y)Liy)Se (x ~ 0.2, y ~ 0.08) was synthesized by hydrothermal methods and structurally characterized by single crystal X-ray diffraction. The crystal structure contains anti-PbO type (Fe(1-y)Liy)Se layers separated by layers of (Li(1-x)Fex)OH. Electrical resistivity and magnetic sus...
1409.3982v1
2014-09-14
Soft striped magnetic fluctuations competing with superconductivity in Fe_{1+x}Te
Neutron spectroscopy is used to investigate the magnetic fluctuations in Fe_{1+x}Te - a parent compound of chalcogenide superconductors. Incommensurate "stripe-like" excitations soften with increased interstitial iron concentration. The energy crossover from incommensurate to stripy fluctuations defines an apparent hou...
1409.4051v1
2014-09-16
Inverse problem for extragalactic transport of ultra-high energy cosmic rays
The energy spectra and composition of ultra-high energy cosmic rays are changing in a course of propagation in the expanding Universe filled with background radiation. We developed a numerical code for solution of inverse problem for cosmic-ray transport equations that allows the determination of average source spectra...
1409.4654v4
2014-09-17
Increased magnetocrystalline anisotropy in epitaxial Fe-Co-C thin films with spontaneous strain
Rare earth free alloys are in focus of permanent magnet research since the accessibility of the elements needed for nowadays conventional magnets is limited. Tetragonally strained iron-cobalt (Fe-Co) has attracted large interest as promising candidate due to theoretical calculations. In experiments, however, the applie...
1409.4952v1
2014-09-25
Characterisation of Glass Electrodes and RPC Detectors for $INO-ICAL$ Experiment
India-based Neutrino Observatory (INO) is a planned neutrino experiment to be build up in southern part of India.The INO observatory will host a 51 kton Iron Calorimeter (ICAL) detector to detect atmospheric neutrinos. Resistive Plate Chamber (RPC) has been chosen as the active detector element for the ICAL experiment....
1409.7184v1
2014-09-26
Superconducting gap structure of BaFe_2(As_{1-x}P_{x})_2
We present a study of the superconducting gap structure in the iron-pnictide series BaFe2(As1-xPx)2. By measuring the variation of the specific heat as a function of temperature and magnetic field we are able to determine the number and Fermi surface location of the nodes in the superconducting gap. In particular, from...
1409.7523v1
2014-09-30
Observation of an electron band above the Fermi level in FeTe$_{0.55}$Se$_{0.45}$ from \emph{in-situ} surface doping
We used \emph{in-situ} potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe$_{0.55}$Se$_{0.45}$. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupie...
1409.8383v2
2014-09-30
Testing non-standard neutrino matter interactions in atmospheric neutrino propagation
We study the effects of non-standard interactions on the oscillation pattern of atmospheric neutrinos. We use neutrino oscillograms as our main tool to infer the role of non-standard interactions (NSI) parameters at the probability level in the energy range, $E \in [1,20]$ GeV and zenith angle range, $\cos \theta \in [...
1409.8472v2
2014-10-02
Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
Majorana fermions are predicted to localize at the edge of a topological superconductor, a state of matter that can form when a ferromagnetic system is placed in proximity to a conventional superconductor with strong spin-orbit interaction. With the goal of realizing a one-dimensional topological superconductor, we hav...
1410.0682v1
2014-10-03
Unexpected impact of magnetic disorder on multiband superconductivity
We analyze how the magnetic disorder affects the properties of the two-band $s_\pm$ and $s_{++}$ models, which are subject of hot discussions regarding iron-based superconductors and other multiband systems like MgB$_2$. We show that there are several cases when the transition temperature $T_c$ is not fully suppressed ...
1410.0832v2
2014-10-13
[$α$/Fe] Abundances of Four Outer M 31 Halo Stars
We present alpha element to iron abundance ratios, [$\alpha$/Fe], for four stars in the outer stellar halo of the Andromeda Galaxy (M 31). The stars were identified as high-likelihood field halo stars by Gilbert et al. (2012) and lie at projected distances between 70 and 140 kpc from M 31's center. These are the first ...
1410.3475v1
2014-10-17
Influence of Electron-Impact Multiple Ionization on Equilibrium and Dynamic Charge State Distributions: A Case Study Using Iron
We describe the influence of electron-impact multiple ionization (EIMI) on the ionization balance of collisionally ionized plasmas. We are unaware of any previous ionization balance calculations that have included EIMI, which is usually assumed to be unimportant. Here, we incorporate EIMI cross-section data into calcul...
1410.4850v1
2014-10-20
Sensitivity for detection of decay of dark matter particle using ICAL at INO
We report on the simulation studies on the possibility of dark matter particle (DMP) decaying into leptonic modes. While not much is known about the properties of dark matter particles except through their gravitational effect, it has been recently conjectured that the so called "anomalous Kolar Events" observed some d...
1410.5182v1
2014-10-21
Possible superconductivity in Sr$_{2}$IrO$_{4}$ probed by quasiparticle interference
Based on the possible superconducting (SC) pairing symmetries recently proposed, the quasiparticle interference (QPI) patterns in electron- and hole-doped Sr$_{2}$IrO$_{4}$ are theoretically investigated. In the electron-doped case, the QPI spectra can be explained based on a model similar to the octet model of the cup...
1410.5512v2
2014-10-23
Superconductivity and phase instability of NH3-free Na-intercalated FeSe1-zSz
The discovery of ThCr2Si2-type AxFe2-ySe2 (A = K, Rb, Cs and Tl) with Tc ~ 30K make much progress in iron-based superconducting field, but their multiple-phase separations are disadvantageous for understanding the origin. On the other hand, for small alkali metals, studies on (Li,Na)FeCu(S,Se)2 and NaFe2-{\delta}S2 sho...
1410.6385v1
2014-10-27
Charge Dynamics in a Correlated Fermion System on a Geometrically Frustrated Lattice
Charge dynamics in an interacting fermionic model on a geometrically frustrated lattice are examined. We analyze a spinless fermion model on a paired triangular lattice, an electronic model for layered iron oxides, in zero and finite temperatures by the exact diagonalization methods. We focus on the two charge ordered ...
1410.7218v1
2014-10-27
Eight billion asteroids in the Oort cloud
The Oort cloud is usually thought of as a collection of icy comets inhabiting the outer reaches of the Solar system, but this picture is incomplete. We use simulations of the formation of the Oort cloud to show that ~4% of the small bodies in the Oort cloud should have formed within 2.5 au of the Sun, and hence be ice-...
1410.7403v1
2014-10-28
Unified picture of the doping dependence of superconducting transition temperatures in alkali metal/ammonia intercalated FeSe
In the recently synthesized Li$_x$(NH$_2$)$_y$(NH$_3$)$_z$Fe$_2$Se$_2$ family of iron chalcogenides a molecular spacer consisting of lithium ions, lithium amide and ammonia separates layers of FeSe. It has been shown that upon variation of the chemical composition of the spacer layer, superconducting transition tempera...
1410.7565v3
2014-10-30
Detection of Neutral Phosphorus in the Near Ultraviolet Spectra of Late-Type Stars
We report the detection of several absorption lines of neutral phosphorus (P, Z=15) in archival near ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We derive phosphorus abundances or interesting upper limits in 14 late-type stars with metallicities spanni...
1410.8539v1
2014-11-01
Glide-Plane Symmetry and Superconducting Gap Structure of Iron-Based Superconductors
We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories have proposed that so-called $\eta$-pairing states with nonzero total momentum can be realized and possess exotic properties such as odd parity spin singl...
1411.0070v2
2014-11-04
In-plane magnetic field vs. temperature phase diagram of a quasi-2D frustrated multiband superconductor
Motivated by the recent discovery of iron-based superconductors, with high critical temperatures and multiple bands crossing the Fermi level, we address the conditions for the presence of chiral superconducting phases configurations in the in-plane magnetic field vs. temperature phase diagram of a quasi-2D frustrated t...
1411.0937v2
2014-11-12
Spontaneous Breakdown of Time-Reversal Symmetry Induced by Thermal Fluctuations
In systems with broken $U(1)$ symmetry, such as superfluids, superconductors or magnets, the symmetry restoration is driven by proliferation of topological defects in the form of vortex loops. Here we discuss that in certain systems the proliferation of topological defects can, by contrast, lead to the breakdown of an ...
1411.3202v2
2014-11-14
The impact of global nuclear mass model uncertainties on $r$-process abundance predictions
Rapid neutron capture or `$r$-process' nucleosynthesis may be responsible for half the production of heavy elements above iron on the periodic table. Masses are one of the most important nuclear physics ingredients that go into calculations of $r$-process nucleosynthesis as they enter into the calculations of reaction ...
1411.3973v1
2014-11-14
A mini review on NiFe-based materials as highly active oxygen evolution reaction electrocatalysts
Oxygen evolution reaction (OER) electrolysis, as an important reaction involved in water splitting and rechargeable metal-air battery, has attracted increasing attention for clean energy generation and efficient energy storage. Nickel/iron (NiFe)-based compounds have been known as active OER catalysts since the last ce...
1411.4677v1
2014-11-19
Stability and magnetization of free-standing and graphene-embedded iron membranes
Inspired by recent experimental realizations of monolayer Fe membranes in graphene perforations, we perform ab initio calculations of Fe monolayers and membranes embedded in graphene in order to assess their structural stability and magnetization. We demonstrate that monolayer Fe has a larger spin magnetization per ato...
1411.5193v1
2014-11-19
Structural ${γ\textrm{-}\varepsilon}$ phase transition in Fe-Mn alloys from CPA+DMFT approach
We present a computational scheme for total energy calculations of disordered alloys with strong electronic correlations. It employs the coherent potential approximation combined with the dynamical mean-field theory and allows one to study the structural transformations. The material-specific Hamiltonians in the Wannie...
1411.5356v3
2014-11-19
Interplay between Kondo effect and Ruderman-Kittel-Kasuya-Yosida interaction
The interplay between the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction and the Kondo effect is expected to provide the driving force for the emergence of many phenomena in strongly correlated electron materials. Two magnetic impurities in a metal are the smallest possible system containing all these ingredients and...
1411.5388v1
2014-11-25
Quantum critical elasticity
We discuss elastic instabilities of the atomic crystal lattice at zero temperature. Due to long-range shear forces of the solid, at such transitions the phonon velocities vanish, if at all, only along certain crystallographic directions, and, consequently, the critical phonon fluctuations are suppressed to a lower dime...
1411.6925v3
2014-11-26
Effect of bombarding steel with Xe$^+$ ions on the surface nanostructure and on pulsed plasma nitriding process
The modification of steel (AISI 316L and AISI 4140) surface morphology and underlying inter-crystalline grains strain due to Xe$^+$ ion bombardment are reported to affect nitrogen diffusion after a pulsed plasma nitriding process. The ion bombardment induces regular nanometric patterns and increases the roughness of th...
1411.7281v1
2014-11-27
Competing superconducting and magnetic order parameters and field-induced magnetism in electron doped Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$
We have studied the magnetic and superconducting properties of Ba(Fe$_{0.95}$Co$_{0.05}$)$_{2}$As$_{2}$ as a function of temperature and external magnetic field using neutron scattering and muon spin rotation. Below the superconducting transition temperature the magnetic and superconducting order parameters coexist and...
1411.7506v1
2014-12-09
An extreme gravitationally redshifted iron line at 4.8 keV in Mrk 876
X-ray spectral lines at unforeseen energies are important because they can shed light on the extreme physical conditions of the environment around the supermassive black holes of active galactic nuclei (AGN). Mrk 876 displays such a line at 4.8 keV rest-frame energy. A possible interpretation of its origin can be found...
1412.3112v1
2014-12-10
M{ö}ssbauer characterization of an unusual high-spin side-on peroxo-Fe3+ species in the active site of superoxide reductase from Desulfoarculus Baarsii. Density functional calculations on related models
Superoxide reductase (SOR) is an Fe protein that catalyzes the reduction of superoxide to give H(2)O(2). Recently, the mutation of the Glu47 residue into alanine (E47A) in the active site of SOR from Desulfoarculus baarsii has allowed the stabilization of an iron-peroxo species when quickly reacted with H(2)O(2) [Math{...
1412.3293v1
2014-12-10
Topological Characters in Fe(Te$_{1-x}$Se$_x$) thin films
We investigate topological properties in the Fe(Te,Se) thin films. We find that the single layer FeTe$_{1-x}$Se$_x$ has nontrivial $Z_2$ topological invariance which originates from the parity exchange at $\Gamma$ point of Brillouin zone. The nontrivial topology is mainly controlled by the Te(Se) height. Adjusting the ...
1412.3375v1
2014-12-11
Transition-Metal Substitutions in Iron Chalcogenides
The $ab$-plane resistivity and Hall effect are studied in Fe$_{1-y}$M$_y$Te$_{0.65}$Se$_{0.35}$ single crystals doped with two transition metal elements, M = Co or Ni, over a wide doping range, $0 \leq y \leq 0.2$. The superconducting transition temperature, $T_{c}$, reaches zero for Co at $y \simeq 0.14$ and for Ni at...
1412.3599v1
2014-12-15
The hard X-ray spectrum of NGC 5506 as seen by NuSTAR
NuSTAR observed the bright Compton-thin, narrow line Seyfert 1 galaxy, NGC 5506, for about 56 ks. In agreement with past observations, the spectrum is well fit by a power law with Gamma~1.9, a distant reflection component and narrow ionized iron lines. A relativistically blurred reflection component is not required by ...
1412.4541v1
2014-12-19
[(Li0.8Fe0.2)OH]FeS and the ferromagnetic superconductors [(Li0.8Fe0.2)OH]Fe(S1-xSex) (0<x<1)
[(Li0.8Fe0.2)OH]FeS and the series [(Li0.8Fe0.2)OH]Fe(S1-xSex) (0<x<1) were synthesized by hydrothermal methods and characterized by X-ray single crystal and powder diffraction, EDX and chemical analysis. Selenium-rich compounds show the coexistence of magnetic ordering with superconductivity known from the pure seleni...
1412.6475v1
2014-12-19
Red Supergiant Stars as Cosmic Abundance Probes. III. NLTE effects in J-band Magnesium lines
Non-LTE calculations for Mg I in red supergiant stellar atmospheres are presented to investigate the importance of non-LTE for the formation of Mg I lines in the NIR J-band. Recent work using medium resolution spectroscopy of atomic lines in the J-band of individual red supergiant stars has demonstrated that technique ...
1412.6527v2
2014-12-22
Superconductivity-induced reentrance of orthorhombic distortion in Ba1-xKxFe2As2
Detailed knowledge of the phase diagram and the nature of the competing magnetic and superconducting phases is imperative for an understanding of the physics of iron-based superconductivity. Here, we show using thermodynamic probes that the phase diagram of the first discovered, and highest Tc, 122-type material, Ba1-x...
1412.7038v2
2014-12-23
Tuning the magnetic anisotropy of single molecules
The magnetism of single atoms and molecules is governed by the atomic scale environment. In general, the reduced symmetry of the surrounding splits the $d$ states and aligns the magnetic moment along certain favorable directions. Here, we show that we can reversibly modify the magnetocrystalline anisotropy by manipulat...
1412.7454v2
2014-12-30
GPU-based acceleration of free energy calculations in solid state physics
Obtaining a thermodynamically accurate phase diagram through numerical calculations is a computationally expensive problem that is crucially important to understanding the complex phenomena of solid state physics, such as superconductivity. In this work we show how this type of analysis can be significantly accelerated...
1412.8754v2
2014-12-31
La$_2$O$_3$Fe$_2$Se$_2$, a Mott insulator on the brink of orbital-selective metalization
La$_2$O$_3$Fe$_2$Se$_2$ can be explained in terms of Mott localization in sharp contrast with the metallic behavior of FeSe and other parent parent compounds of iron superconductors. We demonstrate that the key ingredient that makes La$_2$O$_3$Fe$_2$Se$_2$ a Mott insulator, rather than a correlated metal dominated by t...
1501.00118v1
2015-01-02
Mott-Kondo Insulator Behavior in the Iron Oxychalcogenides
We perform a combined experimental-theoretical study of the Fe-oxychalcogenides (FeO$\emph{Ch}$) series La$_{2}$O$_{2}$Fe$_{2}$O\emph{M}$_{2}$ (\emph{M}=S, Se), which is the latest among the Fe-based materials with the potential \ to show unconventional high-T$_{c}$ superconductivity (HTSC). A combination of incoherent...
1501.00332v1
2015-01-02
Magnetism in Quasi-One-Dimensional A$_2$Cr$_3$As$_3$ (A=K,Rb) superconductors
We predict that the recently discovered quasi-one dimensional superconductors, A$_2$Cr$_3$As$_3$(A=K,Rb), possess strong frustrated magnetic fluctuations and are nearby a novel in-out co-planar magnetic ground state. The frustrated magnetism is very sensitive to c-axis lattice constant and can thus be suppressed by inc...
1501.00412v2
2015-01-03
Single Phase Synthesis and Room temperature Neutron Diffraction Studies on Multiferroic PbFe0.5Nb0.5O3
The Lead-iron-niobate, (PbFe0.5Nb0.5O3 or PFN) was synthesized by low temperature sintering Single Step / Solid State Reaction Method. The 700 C / 2 hrs calcined powder was sintered at 1050 C / 1 hr. The sintered pellets were characterized through X-Ray Diffraction and Neutron Diffraction at room temperature. It is fou...
1501.00553v1
2015-01-05
Nematicity and quantum paramagnetism in FeSe
In common with other iron-based high temperature superconductors, FeSe exhibits a transition to a ``nematic'' phase below 90Kelvin in which the crystal rotation symmetry is spontaneously broken. However, the absence of strong low-frequency magnetic fluctuations near or above the transition has been interpreted as imply...
1501.00844v2
2015-01-05
A novel platform for two-dimensional chiral topological superconductivity
We show that the surface of an $s$-wave superconductor decorated with a two-dimensional lattice of magnetic impurities can exhibit chiral topological superconductivity. If impurities order ferromagnetically and the superconducting surface supports a sufficiently strong Rashba-type spin-orbit coupling, Shiba sub-gap sta...
1501.00999v1
2015-01-07
Pulse radiolysis studies on superoxide reductase from Treponema pallidum
Superoxide reductases (SORs) are small metalloenzymes, which catalyze reduction of O2*- to H2O2. The reaction of the enzyme from Treponema pallidum with superoxide was studied by pulse radiolysis methods. The first step is an extremely fast bi-molecular reaction of the ferrous center with O2, with a rate constant of 6 ...
1501.01443v1
2015-01-07
The flavin reductase ActVB from Streptomyces coelicolor: characterization of the electron transferase activity of the flavoprotein form
The flavin reductase ActVB is involved in the last step of actinorhodin biosynthesis in Streptomyces coelicolor. Although ActVB can be isolated with some FMN bound, this form was not involved in the flavin reductase activity. By studying the ferric reductase activity of ActVB, we show that its FMN-bound form exhibits a...
1501.01465v1
2015-01-07
Identification of iron(III) peroxo species in the active site of the superoxide reductase SOR from Desulfoarculus baarsii
The active site of superoxide reductase SOR consists of an Fe2+ center in an unusual [His4 Cys1] square-pyramidal geometry. It specifically reduces superoxide to produce H2O2. Here, we have reacted the SOR from Desulfoarculus baarsii directly with H2O2. We have found that its active site can transiently stabilize an Fe...
1501.01470v1
2015-01-07
Maximum screening fields of superconducting multilayer structures
It is shown that a multilayer comprised of alternating thin superconducting and insulating layers on a thick substrate can fully screen the applied magnetic field exceeding the superheating fields $H_s$ of both the superconducting layers and the substrate, the maximum Meissner field is achieved at an optimum multilayer...
1501.01512v1
2015-01-08
Sulfurization of Iron in the Dynamic Solar Nebula and Implications for Planetary Compositions
One explanation for the enhanced ratio of volatiles to hydrogen in Jupiter's atmosphere compared to a a gas of solar composition is that the planet accreted volatile-bearing clathrates during its formation. Models, however, suggest that S would be over abundant if clathrates were the primary carrier of Jupiter's volati...
1501.01878v1
2015-01-09
Study of the chemical composition of high energy cosmic rays using the muon LDF of EAS between $10^{17.25}$ eV and $10^{17.75}$ eV
We explore the feasibility of estimating primary cosmic ray composition at high energies from the study of two parameters of Extensive Air Showers (EAS) at ground and underground level with Monte Carlo simulations using the new EPOS and QGSJETII hadronic models tuned with LHC data. Namely, the slope and density at a gi...
1501.02217v1
2015-01-11
Hidden Order as a Source of Interface Superconductivity
Interfacial superconductivity is observed in a variety of heterostructures composed of different materials including superconducting and nonsuperconducting (at appropriate doping and temperatures) cuprates and iron-based pnictides. The origin of this superconductivity remains in many cases unclear. Here, we propose a g...
1501.02505v2
2015-01-16
Slow magnetic fluctuations and superconductivity in fluorine-doped NdFeAsO
Among the widely studied superconducting iron-pnictide compounds belonging to the Ln1111 family (with Ln a lanthanide), a systematic investigation of the crossover region between the superconducting and the antiferromagnetic phase for the Ln = Nd case has been missing. We fill this gap by focusing on the intermediate d...
1501.04005v1
2015-01-19
Raman scattering in superconducting NdO1-xFxBiS2 crystals
The recently discovered layered BiS2-based superconductors have attracted a great deal of interest due to their structural similarity to cuprate and iron-pnictide superconductors. We have performed Raman scattering measurements on two superconducting crystals NdO0.5F0.5BiS2 (Tc = 4.5 K) and NdO0.7F0.3BiS2 (Tc = 4.8 K)....
1501.04453v2
2015-01-20
Shape optimization of an electric motor subject to nonlinear magnetostatics
The goal of this paper is to improve the performance of an electric motor by modifying the geometry of a specific part of the iron core of its rotor. To be more precise, the objective is to smooth the rotation pattern of the rotor. A shape optimization problem is formulated by introducing a tracking-type cost functiona...
1501.04752v1
2015-01-25
Sensorless Battery Internal Temperature Estimation using a Kalman Filter with Impedance Measurement
This study presents a method of estimating battery cell core and surface temperature using a thermal model coupled with electrical impedance measurement, rather than using direct surface temperature measurements. This is advantageous over previous methods of estimating temperature from impedance, which only estimate th...
1501.06160v1
2015-01-26
Measurement of the chemical composition of the ultra-high-energy cosmic rays with the Pierre Auger Observatory
The Pierre Auger Observatory infers the chemical composition of ultra-high-energy cosmic rays through two independent detection techniques. The Fluorescence Detector (FD) measures the longitudinal profile of high energy air showers and can determine the depth of the shower maximum $X_{max}$, which is sensitive to the c...
1501.06325v1
2015-01-28
The Bubble-like Interior of the Core-Collapse Supernova Remnant Cassiopeia A
The death of massive stars is believed to involve aspheric explosions initiated by the collapse of an iron core. The specifics of how these catastrophic explosions proceed remain uncertain due, in part, to limited observational constraints on various processes that can introduce asymmetries deep inside the star. Here w...
1501.07283v1
2015-02-02
Cold condensation of dust in the ISM
The condensation of complex silicates with pyroxene and olivine composition at conditions prevailing in molecular clouds has been experimentally studied. For this purpose, molecular species comprising refractory elements were forced to accrete on cold substrates representing the cold surfaces of surviving dust grains i...
1502.00388v1
2015-02-04
Is inner core seismic anisotropy a marker of plastic flow of cubic iron?
This paper investigates whether observations of seismic anisotropy are compatible with a cubic structure of the inner core Fe alloy. We assume that anisotropy is the result of plastic deformation within a large scale flow induced by preferred growth at the inner core equator. Based on elastic moduli from the literature...
1502.01270v1
2015-02-05
Code intercomparison and benchmark for muon fluence and absorbed dose induced by an 18-GeV electron beam after massive iron shielding
In 1974, Nelson, Kase, and Svenson published an experimental investigation on muon shielding using the SLAC high energy LINAC. They measured muon fluence and absorbed dose induced by a 18 GeV electron beam hitting a copper/water beam dump and attenuated in a thick steel shielding. In their paper, they compared the resu...
1502.01681v1
2015-02-18
UV spectra of iron-doped carbon clusters FeC_n n = 3-6
Electronic transitions of jet-cooled FeC$_n$ clusters ($n = 3 - 6$) were measured between 230 and 300 nm by a mass-resolved 1+1 resonant two-photon ionization technique. Rotational profiles were simulated based on previous calculations of ground state geometries and compared to experimental observations. Reasonable agr...
1502.05310v1
2015-02-19
Low 60Fe abundance in Semarkona and Sahara 99555
Iron-60 (t1/2=2.62 Myr) is a short-lived nuclide that can help constrain the astrophysical context of solar system formation and date early solar system events. A high abundance of 60Fe (60Fe/56Fe= 4x10-7) was reported by in situ techniques in some chondrules from the LL3.00 Semarkona meteorite, which was taken as evid...
1502.05611v1
2015-02-20
Magnetic and Dielectric Properties of Multiferroic BiFeO3 Nanoparticles Synthesized by a Novel Citrate Combustion Method
Single phase BiFeO3 nanoparticles have been successfully synthesized for the first time by a novel citrate combustion method without using any solvent. Well mixed metal nitrates along with citric acid which is used as fuel combust to give BiFeO3 nanoparticles after annealing. These particles are single phase in nature ...
1502.05797v1
2015-02-21
Spin liquid polymorphism in a correlated electron system on the threshold of superconductivity
We report neutron scattering measurements, which reveal spin-liquid polymorphism in a '11' iron chalcogenide superconductor, a poorly-metallic magnetic FeTe tuned towards superconductivity by substitution of a small amount of Tellurium with iso-electronic Sulphur. We observe liquid-like magnetic dynamics, which is desc...
1502.06051v1
2015-02-25
HD188112: Supernova Ia progenitor?
HD188112 is an extremely low mass white dwarf in a close binary system. According to a previous study, the mass of HD188112 is $\sim$0.24 Msun and a lower limit of 0.73 Msun could be put for the mass of its unseen companion, a compact degenarate object. We used HST STIS spectra to measure the rotational broadening of U...
1502.07096v1
2015-02-25
Electron capture cross sections for stellar nucleosynthesis
In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasi-particle random-phase approximation (pn-QRPA) and carry out state-by-state e...
1502.07225v1
2015-02-27
Doping evolution of antiferromagnetism and transport properties in the non-superconducting BaFe2-2xNixCrxAs2
We report elastic neutron scattering and transport measurements on the Ni and Cr equivalently doped iron pnictide BaFe$_{2-2x}$Ni$_{x}$Cr$_{x}$As$_{2}$. Compared with the electron-doped BaFe$_{2-x}$Ni$_{x}$As$_{2}$, the long-range antiferromagnetic (AF) order in BaFe$_{2-2x}$Ni$_{x}$Cr$_{x}$As$_{2}$ is gradually suppre...
1502.07950v1
2015-02-27
Is HE 0436-4717 Anemic? A deep look at a bare Seyfert 1 galaxy
A multi-epoch, multi-instrument analysis of the Seyfert 1 galaxy HE 0436-4717 is conducted using optical to X-ray data from XMM-Newton and Swift (including the BAT). Fitting of the UV-to-X-ray spectral energy distribution shows little evidence of extinction and the X-ray spectral analysis does not confirm previous repo...
1502.07958v1
2015-03-03
Magnetic Fields of Uranus and Neptune: Metallic Fluid Hydrogen
The magnetic fields of the Ice Giant Planets Uranus and Neptune (U/N) are unique in the solar system. Based on a substantial database measured on Earth for representative planetary fluids at representative dynamic pressures up to 200 GPa (2 Mbar) and a few 1000 K, the complex magnetic fields of U/N are (i) probably mad...
1503.01042v2
2015-03-06
NMR evidence for inhomogeneous glassy behavior driven by nematic fluctuations in iron arsenide superconductors
We present $^{75}$As nuclear magnetic resonance spin-lattice and spin-spin relaxation rate data in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ and Ba(Fe$_{1-x}$Cu$_x$)$_2$As$_2$ as a function of temperature, doping and magnetic field. The relaxation curves exhibit a broad distribution of relaxation rates, consistent with inhomogene...
1503.01844v2
2015-03-09
Buffer Aided Relaying Improves Both Throughput and End-to-End Delay
Buffer aided relaying has recently attracted a lot of attention due to the improvement in the system throughput. However, a side effect usually deemed is that buffering at relay nodes results in the increase in packet delays. In this paper, we study the effect of buffering relays on the end-to-end delay of users' data,...
1503.02348v1
2015-03-09
Itinerancy enhanced quantum fluctuation of magnetic moments in iron-based superconductors
We investigate the influence of itinerant carriers on dynamics and fluctuation of local moments in Fe-based superconductors, via linear spin-wave analysis of a spin-fermion model containing both itinerant and local degrees of freedom. Surprisingly against the common lore, instead of enhancing the ($\pi$,0) order, itine...
1503.02653v1
2015-03-12
Anomalous phonon redshift in K-doped BaFe2As2 iron pnictides
The effect of K, Co and P dopings on the lattice dynamics in the BaFe$_2$As$_2$ system is studied by infrared spectroscopy. We focus on the phonon at $\sim$ 253 cm$^{-1}$, the highest energy in-plane infrared-active Fe-As mode in BaFe$_2$As$_2$. Our studies show that the Co and P dopings lead to a blue shift of this ph...
1503.03838v1
2015-03-13
MMonCa: An Object Kinetic Monte Carlo simulator for damage irradiation evolution and defect diffusion
In this work we introduce the Object Kinetic Monte Carlo (OKMC) simulator MMonCa and simulate the defect evolution in three different materials. We start by explaining the theory of OKMC and showing some details of how such theory is implemented by creating generic structures and algorithms in the objects that we want ...
1503.03987v1
2015-03-13
Microscopic Parameters from High-Resolution Specific Heat Measurements on Overdoped BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ Single Crystals
We investigate the electronic specific heat of overdoped BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ single crystals in the superconducting state using high-resolution nanocalorimetry. From the measurements, we extract the doping dependence of the condensation energy, superconducting gap $\Delta$, and related microscopic param...
1503.04088v1
2015-03-18
Super-Hydrophobic Multi-Walled Carbon Nanotube Coatings for Stainless Steel
We have taken advantage of the native surface roughness and the iron content of AISI 316 stainless steel to direct grow multi-walled carbon nanotube (MWCNT) random networks by chemical vapor deposition (CVD) at low-temperature ($< 1000^{\circ}$C), without the addition of any external catalysts or time-consuming pre-tre...
1503.05482v1
2015-03-20
Collapse of the magnetic moment under pressure of AFe$_2$ (A = Y, Zr, Lu and Hf) in the cubic Laves phase
The electronic structures of four Laves phase iron compounds (e.g. YFe$_2$, ZrFe$_2$, LuFe$_2$ and HfFe$_2$) have been calculated by the state-of-the-art full potential electronic structure code. The magnetic moments collapse under hydrostatic pressure. This feature is found to be universal in these materials. Its elec...
1503.06017v1
2015-03-25
Fractional Flux Plateau in Magnetization Curve of Multicomponent Superconductor Loop
Time-reversal symmetry (TRS) may be broken in superconductors with three or more condensates interacting repulsively, yielding two degenerate states specified by chirality of gap functions. We consider a loop of such superconductor with two halves occupied by the two states with opposite chiralities. Fractional flux pl...
1503.07267v3