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2014-06-26 | High-Energy Damping by Particle-Hole Excitations in the Spin-Wave Spectrum of Iron-Based Superconductors | Using a degenerate double-exchange model, we investigate the spin excitation
spectra of iron pnictides. The model consists of local spin moments on each Fe
site, as well as itinerant electrons from the degenerate $d_{xz}$ and $d_{yz}$
orbitals. The local moments interact with each other through antiferromagnetic
$J_{1}... | 1406.6737v3 |
2014-07-02 | Short-range cluster spin glass near optimal superconductivity in BaFe$_{2-x}$Ni$_{x}$As$_{2}$ | High-temperature superconductivity in iron pnictides occurs when electrons
are doped into their antiferromagnetic (AF) parent compounds. In addition to
inducing superconductivity, electron-doping also changes the static
commensurate AF order in the undoped parent compounds into short-range
incommensurate AF order near ... | 1407.0568v1 |
2014-07-07 | Enhancement of Transition Temperature in FexSe0.5Te0.5 Film via Iron Vacancies | The effects of iron deficiency in FexSe0.5Te0.5 thin films (0.8<x<1) on
superconductivity and electronic properties have been studied. A significant
enhancement of the superconducting transition temperature (TC) up to 21K was
observed in the most Fe deficient film (x=0.8). Based on the observed and
simulated structural... | 1407.1575v1 |
2014-07-11 | Superconductivity by transition metal doping in Ca$_{10}$(Fe$_{1-x}$M$_x$As)$_{10}$(Pt$_3$As$_8$) (M = Co, Ni, Cu) | We report the successful substitution of cobalt, nickel, and copper for iron
in the 1038 phase parent compound Ca$_{10}$(FeAs)$_{10}$(Pt$_3$As$_8$) yielding
Ca$_{10}$(Fe$_{1-x}$Co$_x$As)$_{10}$(Pt$_3$As$_8$),
Ca$_{10}$(Fe$_{1-x}$Ni$_x$As)$_{10}$(Pt$_3$As$_8$), and
Ca$_{10}$(Fe$_{1-x}$Cu$_x$As)$_{10}$(Pt$_3$As$_8$), res... | 1407.3100v1 |
2014-07-19 | Magnetic states of iron-based superconducting compounds calculated by using GGA$+U$ method with negative \emph{U} | The magnetic moments per Fe atom in high-$T{_\textrm{c}}$ iron-based
superconducting compounds, BaFe$_{2}$As$_{2}$ and LaFeAsO obtained from the
first-principles calculation with local-spin-density approximation are much
larger than those obtained from experiments. To resolve the contradictory
results between theory an... | 1407.5137v1 |
2014-08-04 | In-gap Bound States Induced by Interstitial Fe Impurities in Iron-based Superconductors | Based on a two-orbit four-band tight binding model, we investigate the
low-lying electronic states around the interstitial excess Fe ions in the
iron-based superconductors by using T-matrix approach. It is shown that the
local density of states at the interstitial Fe impurity (IFI) possesses a
strong resonance inside t... | 1408.0567v1 |
2014-08-12 | Mechano-sysntesis and structural, magnetic and thermal characterization of $α$-Fe nanoparticles embedded in a Wüstite matrix | Magnetic materials for specific applications require an accurate control and
complete comprehension of their magnetic properties. In particular,
nanoparticles embedded in a polycrystalline matrix emerge as good candidates
for applications due to the possibility of tuning the magnetic properties
through interface intera... | 1408.2703v1 |
2014-08-20 | Hot pressing to enhance the transport Jc of Sr0.6K0.4Fe2As2 superconducting tapes | High-performance Sr0.6K0.4Fe2As2 (Sr-122) tapes have been successfully
fabricated using hot pressing (HP) process. The effect of HP temperatures
(850-925 C) on the c-axis texture, resistivity, Vickers micro-hardness,
microstructure and critical current properties has been systematically studied.
Taking advantage of hig... | 1408.4516v2 |
2014-08-29 | What You Should Know About Megaprojects, and Why: An Overview | This paper takes stock of megaproject management, an emerging and hugely
costly field of study. First, it answers the question of how large megaprojects
are by measuring them in the units mega, giga, and tera, concluding we are
presently entering a new "tera era" of trillion-dollar projects. Second, total
global megapr... | 1409.0003v1 |
2014-09-04 | Anomalous High-Energy Electronic Interaction in Iron-Based Superconductor | Strong electron interactions in solids increase effective mass, and shrink
the electronic bands [1]. One of the most unique and robust experimental facts
about iron-based superconductors [2-4] is the renormalization of the conduction
band by factor of 3 near the Fermi level [5-9]. Obviously related to
superconductivity... | 1409.1537v1 |
2014-09-05 | The electronic structure of rare-earth iron silicide R2Fe3Si5 superconductors | The electronic structures of R2Fe3Si5 (where R = Lu, Tm, Er, Tb, Yb)
intermetallics have been calculated from first principles in local-spin density
(LSDA) and LSDA + U approaches. The majority of rare-earth iron silicides,
except for the heavy-fermion Yb-based compound, exhibit almost equal values of
density of states... | 1409.1861v1 |
2014-09-10 | $X_{max}^μ$ vs. $N^μ$ from Extensive Air Showers as estimator for the mass of primary UHECR's. Application for the Pierre Auger Observatory | We study the possibility of primary mass estimation for Ultra High Energy
Cosmic Rays (UHECR's) using the $X_{max}^{\mu}$ (the height where the number of
muons produced on the core of Extensive Air Showers (EAS) is maximum) and the
number $N^{\mu}$ of muons detected on ground. We use the 2D distribution -
$X_{max}^{\mu... | 1409.2972v1 |
2014-09-11 | Challenges in the Theoretical Description of Nanoparticle Reactivity: Nano Zero-Valent Iron | The reactivity of iron atoms, clusters and nanoparticles (nZVI) is of
increasing interest owing to their important practical applications, ranging
from the steel industry to water remediation technologies. Here, we provide an
overview of computational methods and models that can be applied to study nZVI
reactions and d... | 1409.3529v1 |
2014-09-23 | The effect of Cr impurity to superconductivity in electron-doped BaFe2-xNixAs2 | We use transport and magnetization measurements to study the effect of
Cr-doping to the phase diagram of the electron-doped superconducting
BaFe2-xNixAs2 iron pnictides. In principle, adding Cr to electron-doped
BaFe2-xNixAs2 should be equivalent to the effect of hole-doping. However, we
find that Cr doping suppresses ... | 1409.6402v1 |
2014-09-29 | Fe I Oscillator Strengths for Transitions from High-lying Even-Parity Levels | New radiative lifetimes, measured to $\pm$ 5 % accuracy, are reported for 31
even-parity levels of Fe I ranging from 45061 cm$^{-1}$ to 56842 cm$^{-1}$.
These lifetimes have been measured using single-step and two-step time-resolved
laser-induced fluorescence on a slow atomic beam of iron atoms. Branching
fractions hav... | 1409.8142v1 |
2014-09-30 | Direct observation of spin-orbit coupling in iron-based superconductors | Spin-orbit coupling (SOC) is a fundamental interaction in solids which can
induce a broad spectrum of unusual physical properties from topologically
non-trivial insulating states to unconventional pairing in superconductors. In
iron-based superconductors (IBS) its role has so far been considered
insignificant with the ... | 1409.8669v2 |
2014-10-10 | BaFe$_2$Se$_3$: a high $T_{\rm C}$ magnetic multiferroic with large ferrielectric polarization | The iron-selenides are important because of their superconducting properties.
Here, an unexpected phenomenon is predicted to occur in an iron-selenide
compound with a quasi-one-dimensional ladder geometry: BaFe$_2$Se$_3$ should be
a magnetic ferrielectric system, driven by its magnetic block order via
exchange strictio... | 1410.2682v1 |
2014-10-12 | Comment on "Multiorbital Effects on the Transport and the Superconducting Fluctuations in LiFeAs" | In the commented work (PRL 109, 187005 (2012)), Rullier-Albenque et al.
present measurements of transverse magnetoresistivity above the transition
temperature Tc in clean LiFeAs. By analyzing their data, these authors conclude
that the conductivity induced by fluctuations follows a two-dimensional (2D)
behavior even cl... | 1410.3139v3 |
2014-10-13 | Dusty tails of evaporating exoplanets. I. Constraints on the dust composition | Recently, two exoplanet candidates have been discovered, KIC 12557548b and
KOI-2700b, whose transit profiles show evidence for a comet-like tail of dust
trailing the planet, thought to be fed by the evaporation of the planet's
surface. We aim to put constraints on the composition of the dust ejected by
these objects fr... | 1410.3494v1 |
2014-10-17 | Coexistence of ferromagnetism and superconductivity in iron based pnictides: a time resolved magnetooptical study | Ferromagnetism and superconductivity are antagonistic phenomena. Their
coexistence implies either a modulated ferromagnetic order parameter on a
lengthscale shorter than the superconducting coherence length or a weak
exchange coupling between the itinerant superconducting electrons and the
localized ordered spins. In s... | 1410.4651v1 |
2014-10-21 | Searching for high magnetization density in bulk Fe: the new metastable Fe$_6$ phase | We report the discovery of a new allotrope of iron by first principles
calculations. This phase has $Pmn2_1$ symmetry, a six-atom unit cell (hence the
name Fe$_6$), and the highest magnetization density (M$_s$) among all known
crystalline phases of iron. Obtained from the structural optimizations of the
Fe$_3$C-cementi... | 1410.5875v1 |
2014-10-23 | On the origin of the electronic anisotropy in iron pnicitde superconductors | We use polarization-resolved Raman spectroscopy to study the anisotropy of
the electronic characteristics of the iron-pnictide parent compounds
$A$Fe$_{2}$As$_{2}$ ($A$~=~Eu, Sr). We demonstrate that above the structural
phase transition at Ts the dynamical anisotropic properties of the 122
compounds are governed by th... | 1410.6452v1 |
2014-10-23 | Critical Quadrupole Fluctuations and Collective Modes in Iron Pnictide Superconductors | The multiband nature of iron pnictides gives rise to a rich
temperature-doping phase diagram of competing orders and a plethora of
collective phenomena. At low dopings, the tetragonal-to-orthorhombic structural
transition is closely followed by a spin density wave transition both being in
close proximity to the superco... | 1410.6456v2 |
2014-10-24 | Strong Coupling Between Whispering Gallery Photons and Spin States of Iron Group Impurity Ions | Interaction of Whispering Gallery Modes (WGM) with dilute spin ensembles in
solids is an interesting paradigm of Hybrid Quantum Systems potentially
beneficial for Quantum Signal Processing applications. In the present work, WGM
spectroscopy of Rare-Earth doped YSO crystal reveals the existence of Iron
Group Ion (IGI) c... | 1410.6578v4 |
2014-10-24 | Investigation of the crystal and magnetic structures of the trigonal multiferroic iron-boracite Fe3B7O13(OH) | We have investigated the crystal and magnetic structures of the trigonal
iron-boracite Fe3B7O13X with X = OH by neutron diffraction. Neutron diffraction
enables us to locate the hydrogen atom of the hydroxyl group and determine the
magnetic ground state of this member of the multiferroic boracite family. No
evidence wa... | 1410.6602v1 |
2014-11-06 | Study of magnetic iron nitride thin films deposited by high power impulse magnetron sputtering | In this work, we studied phase formation, structural and magnetic properties
of iron-nitride (Fe-N) thin films deposited using high power impulse magnetron
sputtering (HiPIMS) and direct current magnetron sputtering (dc-MS). The
nitrogen partial pressure during deposition was systematically varied both in
HiPIMS and dc... | 1411.1614v2 |
2014-11-12 | Block magnetic excitations in the orbitally selective Mott insulator BaFe2Se3 | Iron pnictides and selenides display a variety of unusual magnetic phases
originating from the interplay between electronic, orbital, and lattice degrees
of freedom. Using powder inelastic neutron scattering on the two-leg ladder
BaFe2Se3, we fully characterize the static and dynamic spin correlations
associated with t... | 1411.3337v2 |
2014-11-18 | High critical current density in textured Ba-122/Ag tapes fabricated by scalable rolling process | The industrial manufacturing of the long-length iron-pnictide wires and tapes
requires simple and low-cost technology. Although the transport critical
current density of the FeAs-122 tapes has already achieved the practical
application level, their fabrication procedures are relatively complicated or
required specializ... | 1411.4720v2 |
2014-11-19 | QSGW+DMFT: an electronic structure scheme for the iron pnictides and beyond | While in strongly correlated materials one often focuses on local electronic
correlations, the influence of non-local exchange and correlation effects
beyond band-theory can be pertinent in systems with more extended orbitals.
Thus in many compounds an adequate theoretical description requires the joint
treatment of lo... | 1411.5180v1 |
2014-11-24 | Superconductivity In K- And Na- Doped Bafe2as2: What Can We Learn From Heat Capacity And Pressure Dependence of Tc | A brief overview of changes in the superconducting transition temperature
under pressure and evolution of specific heat capacity jump at Tc for two
related families of iron - based superconductors, Ba{1-x}KxFe2As2 (0.2 < x <
1.0) and Ba{1-x}NaxFe2As2 (0.2 < x < 0.9) will be given. For Ba{1-x}KxFe2As2
the specific heat ... | 1411.6485v1 |
2014-11-27 | Short-Time Dynamics of Fe2/V13 Magnetic Superlattice Models | Critical relaxation from a low-temperature fully ordered state of Fe2/V13
iron-vanadium magnetic superlattice models has been studied using the method of
short-time dynamics. Systems with three variants of the ratio R of inter- to
intralayer exchange coupling have been considered. Particles with N = 262144
spins have b... | 1411.7546v1 |
2014-12-02 | Unabridged phase diagram for single-phased FeSexTe1-x thin films | A complete phase diagram and its corresponding physical properties are
essential prerequisites to understand the underlying mechanism of iron based
superconductivity. For the structurally simplest 11 (FeSeTe) system, earlier
attempts using bulk samples have not been able to do so due to the fabrication
difficulties. He... | 1412.0888v1 |
2014-12-02 | Quantum Criticality in the 122 Iron Pnictide Superconductors Emerging from Orbital-Selective Mottness | The twin issues of the nature of the normal state and competing order(s) in
the iron arsenides are central to understanding their unconventional, high-Tc
superconductivity. We use a combination of transport anisotropy measurements on
detwinned Sr(Fe(1-x)Co(x))2As2 single crystals and local density approximation
plus dy... | 1412.1034v2 |
2014-12-04 | Coexistence pressure for a martensitic transformation from theory and experiment: revisiting the bcc-hcp transition of iron under pressure | The coexistence pressure of two phases is a well-defined point at fixed
temperature. In experiment, however, due to non-hydrostatic stresses and a
stress-dependent potential energy barrier, different measurements yield
different ranges of pressure with a hysteresis. Accounting for these effects,
we propose an inequalit... | 1412.1849v2 |
2014-12-07 | Suppression of superconductivity and structural phase transition against pressure in Ca$_{10}$(Ir$_{4}$As$_{8}$)(Fe$_{2-x}$Ir$_{x}$As$_{2}$)$_{5}$ | We measured the pressure dependence of in-plane resistivity $\rho_{ab}$ in
the recently-discovered iron-based superconductor
Ca$_{10}$(Ir$_{4}$As$_{8}$)(Fe$_{2-x}$Ir$_{x}$As$_{2}$)$_{5}$, which shows a
unique structural phase transition in the absence of magnetic ordering, with a
superconducting transition temperature ... | 1412.2317v1 |
2014-12-09 | Spin excitations in the nematic phase and the metallic stripe spin-density wave phase of iron pnictides | We present a general study of the magnetic excitations within a weak-coupling
five-orbital model relevant to itinerant iron pnictides. As a function of
enhanced electronic correlations, the spin excitations in the symmetry broken
spin-density wave phase evolve from broad low-energy modes in the limit of weak
interactio... | 1412.2912v1 |
2014-12-09 | Optimization of a Non-arsenic Iron-based Superconductor for Wire Fabrication | We report on the optimization of synthesis of iron-selenide (non-arsenic)
superconducting powders that are based on '122' composition, with optimal Tc =
38 K and Jc = 10^5 A/cm2 (4 K). We also report on the wire proof-of concept for
these materials, by producing ~ 40 ft of wire that produce Ic. The 122
selenides are mo... | 1412.3065v1 |
2015-01-07 | Temperature dependence of iron local magnetic moment in phase-separated superconducting chalcogenide | We have studied local magnetic moment and electronic phase separation in
superconducting K$_{x}$Fe$_{2-y}$Se$_2$ by x-ray emission and absorption
spectroscopy. Detailed temperature dependent measurements at the Fe K-edge have
revealed coexisting electronic phases and their correlation with the transport
properties. By ... | 1501.01558v1 |
2015-01-09 | First-principles theory of electron-spin fluctuation coupling and superconducting instabilities in iron selenide | We present first-principles calculations of the coupling of quasiparticles to
spin fluctuations in iron selenide and discuss which types of superconducting
instabilities this coupling gives rise to. We find that strong
antiferromagnetic stripe-phase spin fluctuations lead to large coupling
constants for superconducting... | 1501.02200v1 |
2015-01-15 | Strain effects in monolayer Iron-Chalcogenide superconductors | The successful fabrication of one monolayer FeSe on SrTiO$_{3}$ represented a
real breakthrough in searching for high-T$_{c}$ Fe-based superconductors (Ref.
1). Motivated by this important discovery, we studied the effects of tensile
strain on one monolayer and bulk iron-chalcogenide superconductors (FeSe and
FeTe), sh... | 1501.03630v1 |
2015-01-16 | Spectroscopic Studies of Iron-based Superconductors, Multi-ferroic Oxides and Double-perovskite: Phonons, Electronic and Spin Excitations | Raman spectroscopy is a very powerful probe to study the nature of
quasi-particle excitations in condensed matter physics. The work presented in
this thesis is focused on two different families of novel materials, namely the
iron-based superconductors (FeBS), multiferroic oxides and double perovskite.
Although the prop... | 1501.04055v1 |
2015-01-19 | Superconductivity at 52 K in hydrogen-substituted LaFeAsO1-xHx under high pressure | The 1111-type iron-based superconductor LnFeAsO1-xFx (Ln stands for
lanthanide) is the first material with a Tc above 50 K, other than cuprate
superconductors. Electron doping into LaFeAsO by H, rather than F, revealed a
double-dome-shaped Tc-x diagram, with a first dome (SC1, 0.05<x<0.20) and a
second dome (SC2, 0.2<x... | 1501.04544v1 |
2015-01-20 | Structural, electronic, and magnetic properties of tris(8-hydroxyquinoline)iron(III) molecules and its magnetic coupling with ferromagnetic surface: first-principles study | Using first-principles calculations, we have systematically investigated the
structural, electronic, and magnetic properties of facial (fac-) and meridional
(mer-) tris(8-hydroxyquinoline)iron(III) (Feq3) molecules and their interaction
with ferromagnetic substrate. Our calculation results show that for the
isolated Fe... | 1501.04926v1 |
2015-01-23 | Antiferroquadrupolar and Ising-Nematic Orders of a Frustrated Bilinear-Biquadratic Heisenberg Model and Implications for the Magnetism of FeSe | Motivated by the properties of the iron chalcogenides, we study the phase
diagram of a generalized Heisenberg model with frustrated bilinear-biquadratic
interactions on a square lattice. We identify zero-temperature phases with
antiferroquadrupolar and Ising-nematic orders. The effects of quantum
fluctuations and inter... | 1501.05926v4 |
2015-01-26 | A Large Sample of Am Candidates from LAMOST Data Release 1 | We present a sample of metallic-line star (Am) candidates from the Large sky
Area Multi-Object fiber Spectroscopic Telescope Data Release one (LAMOST DR1).
According to the characteristic of under-abundance of calcium and overabundance
of iron element of Am stars, we propose an empirical separation curve derived
from l... | 1501.06233v1 |
2015-01-28 | Dynamics and stability of icosahedral Fe-Pt nanoparticles | The structure, dynamics and stability of Fe-Pt nanoparticles have been
investigated using DFT-based techniques: total energy calculations and DFT
molecular dynamics. The investigated systems included multi-shell and
disordered nanoparticles of iron and platinum. The study is concerned with
icosahedral particles with ma... | 1501.07143v2 |
2015-01-28 | 57Fe Mossbauer study of Lu2Fe3Si5 iron silicide superconductor | With the advent of Fe-As based superconductivity it has become important to
study how superconductivity manifests itself in details of 57Fe Mossbauer
spectroscopy of conventional, Fe - bearing superconductors. To this end, the
iron-based superconductor Lu2Fe3Si5 has been studied by 57Fe Mossbauer
spectroscopy over the ... | 1501.07254v2 |
2015-02-12 | Strong $(π,0)$ spin fluctuations in $β$-FeSe observed by neutron spectroscopy | We have performed powder inelastic neutron scattering measurements on the
unconventional superconductor $\beta$-FeSe ($T_{\rm c} \simeq 8\,\mathrm{K}$).
The spectra reveal highly dispersive paramagnetic fluctuations emerging from
the square-lattice wave vector $(\pi,0)$ extending beyond 80 meV in energy.
Measurements a... | 1502.03838v2 |
2015-02-15 | In situ observation of phase separation and hierarchical microstructure of KxFe2-ySe2 single crystals | The nature of the phase separation in KxFe2-ySe2 single crystals is not well
understood. Here, temperature dependent SEM images provide compelling evidence
that phase separation corresponds to a nucleation and growth process rather
than a spinodal decomposition. The superconducting phase is the remnant of high
temperat... | 1502.04335v1 |
2015-02-16 | Tuning electronic correlations in transition metal pnictides: chemistry beyond the valence count | The effects of electron-electron correlations on the low-energy electronic
structure and their relationship with unconventional superconductivity are
central aspects in the research on the iron-based pnictide superconductors.
Here we use soft X-ray angle-resolved photoemission spectroscopy (SX-ARPES) to
study how elect... | 1502.04565v1 |
2015-02-20 | Competing magnetic double-Q phases and superconductivity-induced re-entrance of C2 magnetic stripe order in iron pnictides | We perform a microscopic theoretical study of the generic properties of
competing magnetic phases in iron pnictides. As a function of electron filling
and temperature, the magnetic stripe (single-Q) order forms a dome, but
competing non-collinear and non-uniform double-Q phases exist at the foot of
the dome in agreemen... | 1502.05859v2 |
2015-02-20 | Valence fluctuations in a lattice of magnetic molecules: application to iron(II) phtalocyanine molecules on Au(111) | We study theoretically a square lattice of the organometallic Kondo adsorbate
iron(II) phtalocyanine (FePc) deposited on top of Au(111), motivated by recent
scanning tunneling microscopy experiments. We describe the system by means of
an effective Hubbard-Anderson model, where each molecule has degenerate
effective $d-... | 1502.05995v1 |
2015-02-23 | Spin fluctuations in iron pnictides and chalcogenides: From antiferromagnetism to superconductivity | The present article reviews recent experimental investigations of spin
dynamics in iron-based superconductors and their parent compounds by means of
inelastic neutron scattering. It mainly focuses on the most contemporary
developments in this field, pertaining to the observations of magnetic resonant
modes in new super... | 1502.06570v1 |
2015-02-25 | Robust $s_{\pm}$-wave superconductivity against multi-impurity in iron-based superconductors | Effects of disorder on electron-doped iron pnictides are investigated
systematically based on self-consistent Bogoliubov-de Gennes equations.
Multiply impurities with same scattering potential (SP) are randomly
distributed in a square lattice. Probability distribution functions of
normalized order parameters for differ... | 1502.07305v1 |
2015-03-09 | Magnetic Cluster Expansion model for random and ordered magnetic face-centered cubic Fe-Ni-Cr alloys | A Magnetic Cluster Expansion (MCE) model for ternary face-centered cubic
Fe-Ni-Cr alloys has been developed using DFT data spanning binary and ternary
alloy configurations. Using this MCE model Hamiltonian, we perform Monte Carlo
simulations and explore magnetic structures of alloys over the entire range of
alloy compo... | 1503.02481v1 |
2015-03-19 | Oxygen, α-element and iron abundance distributions in the inner part of the Galactic thin disc | We derived elemental abundances in 27 Cepheids, the great majority situated
within a zone of Galactocentric distances ranging from 5 to 7 kpc. One star of
our sample, SU Sct, has a Galactocentric distance of about 3 kpc, and thus
falls in a poorly investigated region of the inner thin disc. Our new results,
combined wi... | 1503.05898v1 |
2015-03-27 | Temperature and composition phase diagram in the iron-based ladder compounds Ba1-xCsxFe2Se3 | We investigated the iron-based ladder compounds (Ba,Cs)Fe$_2$Se$_3$. Their
parent compounds, BaFe$_2$Se$_3$ and CsFe$_2$Se$_3$, have different space
groups, formal valences of Fe and magnetic structures. Electrical resistivity,
specific heat, magnetic susceptibility, X-ray diffraction and powder neutron
diffraction mea... | 1503.08129v1 |
2015-04-09 | Low-field microwave absorption and magnetoresistance in iron nanostructures grown by electrodeposition on n-type lightly-doped silicon substrates | In this study we investigate magnetic properties, surface morphology and
crystal structure in iron nanoclusters electrodeposited on lightly-doped (100)
n-type silicon substrates. Our goal is to investigate the spin injection and
detection in the Fe/Si lateral structures. The samples obtained under electric
percolation ... | 1504.02508v1 |
2015-04-14 | Strong similarities between the local electronic structure of insulating iron pnictide and lightly doped cuprate | One of the major puzzles regarding unconventional superconductivity is how
some of the most interesting superconductors are related to an insulating phase
that lies in close proximity. Here we report scanning tunneling microscopy
studies of the local electronic structure of Cu doped NaFeAs across the
superconductor to ... | 1504.03515v1 |
2015-04-14 | Pressure Induced Enhancement of Superconductivity in LaRu2P2 | To explore new superconductors beyond the copper-based and iron-based systems
is very important. The Ru element locates just below the Fe in the periodic
table and behaves like the Fe in many ways. One of the common thread to induce
high temperature superconductivity is to introduce moderate correlation into
the system... | 1504.03652v1 |
2015-04-14 | Vestigial chiral and charge orders from bidirectional spin-density waves: Application to the iron-based superconductors | Recent experiments in optimally hole-doped iron arsenides have revealed a
novel magnetically ordered ground state that preserves tetragonal symmetry,
consistent with either a charge-spin density wave (CSDW), which displays a
non-uniform magnetization, or a spin-vortex crystal (SVC), which displays a
non-collinear magne... | 1504.03656v3 |
2015-04-20 | Raman scattering as a probe of nematic correlations | We use the symmetry constrained low energy effective Hamiltonian of iron
based superconductors to study the Raman scattering in the normal state of
underdoped iron-based superconductors. The incoming and scattered Raman photons
couple directly to orbital fluctuations and indirectly to the spin
fluctuations. We computed... | 1504.05054v2 |
2015-04-23 | The origin of anomalous diffusion in iron mononitride thin films | We have studied the origin of a counter intuitive diffusion behavior of Fe
and N atoms in a iron mononitride (FeN) thin film. It was observed that
in-spite of a larger atomic size, Fe tend to diffuse more rapidly than smaller
N atoms. This only happens in the N-rich region of Fe-N phase diagram, in the
N-poor regions, ... | 1504.06047v1 |
2015-04-28 | Emergent loop-nodal s$_\pm$-wave superconductivity in CeCu$_2$Si$_2$: similarities to the iron-based superconductors | Heavy-fermion superconductors are prime candidates for novel electron-pairing
states due to the spin-orbital coupled degrees of freedom and electron
correlations. Superconductivity in CeCu$_2$Si$_2$ discovered in 1979, which is
a prototype of unconventional (non-BCS) superconductors in strongly correlated
electron syst... | 1504.07312v1 |
2015-05-09 | Exploration of new superconductors and functional materials and fabrication of superconducting tapes and wires of iron pnictides | This paper reviews the highlights of a 4-years-long research project
supported by the Japanese Government to explore new superconducting materials
and relevant functional materials. The project found several tens of new
superconductors by examining ~1000 materials, each of which was chosen by
Japanese team member exper... | 1505.02240v1 |
2015-05-19 | Electronic structure of NaFeAs superconductor: LDA+DMFT calculations compared with ARPES experiment | We present the results of extended theoretical LDA+DMFT calculations for a
new iron-pnictide high temperature superconductor NaFeAs compared with the
recent high quality angle-resolved photoemission (ARPES) experiments on this
system [1]. The universal manifestation of correlation effects in
iron-pnictides is narrowing... | 1505.04963v1 |
2015-05-20 | Effect of Al doping on phase formation and thermal stability of iron nitride thin films | In the present work, we systematically studied the effect of Al doping on the
phase formation of iron nitride (Fe-N) thin films. Fe-N thin films with
different concentration of Al (Al=0, 2, 3, 6, and 12 at.%) were deposited using
dc magnetron sputtering by varying the nitrogen partial pressure between 0 to
100%. The st... | 1505.05371v1 |
2015-05-21 | Abundances in the atmosphere of the metal-rich planet-host star HD 77338 | Abundances of Fe, Si, Ni, Ti, Na, Mg, Cu, Zn, Mn, Cr and Ca in the atmosphere
of the K-dwarf HD 77338 are determined and discussed. HD 77338 hosts a hot
Uranus-like planet and is currently the most metal-rich single star to host any
planet. Determination of abundances was carried out in the framework of a
self-consiste... | 1505.05843v1 |
2015-06-02 | Coexistence of antiferromagnetic and ferromagnetic spin correlations in SrCo2As2 revealed by 59Co and 75As NMR | In nonsuperconducting, metallic paramagnetic SrCo2As2, inelastic neutron
scattering measurements have revealed strong stripe-type $\chi$(q) = ($\pi$,0)
antiferromagnetic (AFM) spin correlations. Here, using nuclear magnetic
resonance (NMR) measurements on 59Co and 75As nuclei, we demonstrate that
stronger ferromagnetic... | 1506.00994v2 |
2015-06-03 | Magneto-structural transformations via a solid-state nudged elastic band method: Application to iron under pressure | We extend the solid-state nudged elastic band method to handle a
non-conserved order parameter - in particular, magnetization, that couples to
volume and leads to many observed effects in magnetic systems. We apply this
formalism to the well-studied magneto-volume collapse during the
pressure-induced transformation in ... | 1506.01403v1 |
2015-06-15 | Tuning orbital-selective correlation effects in superconducting Rb$_{0.75}$Fe$_{1.6}$Se$_{2-z}$S$_z$ | We report on terahertz time-domain spectroscopy on superconducting and
metallic iron chalcogenides Rb$_{0.75}$Fe$_{1.6}$Se$_{2-z}$S$_z$. The
superconducting transition is reduced from $T_c=$ 32 K ($z=0$) to 22 K
($z=1.0$), and finally suppressed ($z=1.4$) by isoelectronic substitution of Se
with S. Dielectric constant ... | 1506.04614v3 |
2015-06-15 | The effects of Coulomb interactions on the superconducting gaps in iron-based superconductors | Recent angle-resolved photoemission spectroscopy measurements of Co-doped
LiFeAs report a large and robust superconducting gap on the $\Gamma$-centered
hole band that lies 8 meV below the Fermi level. We show that, unlike a
conventional superconductor described by BCS theory, a multiband system with
strong interband Co... | 1506.04762v3 |
2015-06-29 | First-principle study of antimony doping effects on the iron-based superconductor CaFe(Sb$_{x}$As$_{1-x}$)$_{2}$ | We study antimony doping effects in the iron-based superconductor
CaFe(Sb$_{x}$As$_{1-x}$)$_{2}$ by using the first-principle calculation. The
calculations reveal that the substitution of the doped antimony atom into As of
the chainlike As layers is more stable than that in FeAs layers. This
prediction can be checked b... | 1506.08515v1 |
2015-07-07 | Anisotropy of iron-platinum-arsenide Ca10(PtnAs8)(Fe2-xPtxAs2)5 single crystals | The upper critical field Hc2 anisotropy of Ca10(PtnAs8)(Fe2-xPtxAs2)5 (n = 3,
4) single crystals with long FeAs interlayer distance (d) was studied by
angular dependent resistivity measurements. A scaling of the angular dependent
resistivity was realized for both single crystals using the anisotropic
Ginzburg-Landau (A... | 1507.01987v1 |
2015-07-10 | Proper motions in Terzan 5: membership of the multi-iron sub-populations and first constrain to the orbit | By exploiting two sets of high-resolution images obtained with HST ACS/WFC
over a baseline of ~10 years we have measured relative proper motions of
~70,000 stars in the stellar system Terzan 5. The results confirm the
membership of the three sub-populations with different iron abudances
discovered in the system. The or... | 1507.03020v1 |
2015-07-16 | Magnetic penetration depth in disordered iron-based superconductors | We study the effect of disorder on the London penetration depth in iron-based
superconductors. The theory is based on a two-band model with
quasi-two-dimensional Fermi surfaces, which allows for the coexistence region
in the phase diagram between magnetic and superconducting states in the
presence of intraband and inte... | 1507.04762v1 |
2015-07-17 | Testing the Kerr Paradigm with X-ray Observations | Astrophysical black hole candidates are thought to be the Kerr black holes of
general relativity, but the actual nature of these objects has still to be
confirmed. The continuum-fitting and the iron line methods are currently the
only available techniques to probe the spacetime geometry around these bodies
and test the... | 1507.05036v1 |
2015-07-20 | Minimum X-ray source size for a lamp-post corona in light-bending models for AGN | The lamppost model is often used to describe the X-ray source geometry in
AGN, where an infinitesimal point source is located on the black hole spin
axis. This is especially invoked for Narrow Line Seyfert 1 (NLS1) galaxies,
where an extremely broad iron line seen in episodes of low X-ray flux can both
be explained by ... | 1507.05564v1 |
2015-07-28 | Deep X-ray spectroscopy and imaging of the Seyfert 2 galaxy, ESO 138-G001 | We present a spectral and imaging analysis of the XMM-Newton and Chandra
observations of the Seyfert 2 galaxy ESO138-G001, with the aim of
characterizing the circumnuclear material responsible for the soft (0.3-2.0
keV) and hard (5-10 keV) X-ray emission. We confirm that the source is absorbed
by Compton-thick gas. How... | 1507.07708v1 |
2015-07-31 | Emergent Kondo scaling in iron-based superconductors AFe2As2 (A = K, Rb, Cs) | Unconventional superconductivity from heavy fermion (HF) is always observed
in f-electron systems, in which Kondo physics between localized f-electrons and
itinerant electrons plays an essential role. Whether HF superconductivity could
be achieved in other systems without f electrons, especially for d-electron
systems,... | 1507.08732v2 |
2015-08-04 | Toward precision mass measurements of neutron-rich nuclei relevant to $r$-process nucleosynthesis | The open question of where, when, and how the heavy elements beyond iron
enrich our Universe has triggered a new era in nuclear physics studies.\ Of all
the relevant nuclear physics inputs, the mass of very neutron-rich nuclides is
a key quantity for revealing the origin of heavy elements beyond iron.\
Although the pre... | 1508.00695v1 |
2015-08-17 | Engineering the magnetic anisotropy of atomic-scale nanostructure under electric field | Atomic-scale magnetic nanostructures are promising candidates for future
information processing devices. Utilizing external electric field to manipulate
their magnetic properties is an especially thrilling project. Here, by careful
identifying different contributions of each atomic orbital to the magnetic
anisotropy en... | 1508.03917v1 |
2015-08-24 | A template method for measuring the iron spectrum in cosmic rays with Cherenkov telescopes | The energy-dependent abundance of elements in cosmic rays plays an important
role in understanding their acceleration and propagation. Most current results
are obtained either from direct measurements by balloon- or satellite-borne
detectors, or from indirect measurements by air shower detector arrays on the
Earth's su... | 1508.05823v1 |
2015-09-07 | Valence fluctuations and empty-state resonance for Fe adatom on a surface | We report on the formation of the high-energy empty-state resonance in the
electronic spectrum of the iron adatom on the Pt(111) surface. By using the
combination of the first-principles methods and the finite-temperature exact
diagonalization approach, we show that the resonance is the result of the
valence fluctuatio... | 1509.02109v2 |
2015-09-29 | The far-ultraviolet spectra of "cool" PG1159 stars | We present a comprehensive study of Far Ultraviolet Spectroscopic Explorer
(FUSE) spectra (912-1190 A) of two members of the PG1159 spectral class, which
consists of hydrogen-deficient (pre-) white dwarfs with effective temperatures
in the range Teff = 75,000-200,000 K. As two representatives of the cooler
objects, we ... | 1509.08927v1 |
2015-10-02 | Electronic structure and magnetic properties of FeTe, BiFeO$_3$, SrFe$_{12}$O$_{19}$ and SrCoTiFe$_{10}$O$_{19}$ compounds | The electronic energy structures and magnetic properties of iron-based
compounds with group VI elements (FeTe, BiFeO$_3$, SrFe$_{12}$O$_{19}$ and
SrCoTiFe$_{10}$O$_{19}$) are studied using the density functional theory (DFT)
methods. Manifestations of different types of chemical bonds in magnetism of
these compounds ar... | 1510.00513v1 |
2015-10-05 | Spin-Driven Nematic Instability of the Multi-Orbital Hubbard Model: Application to Iron-Based Superconductors | Nematic order resulting from the partial melting of density-waves has been
proposed as the mechanism to explain nematicity in iron-based superconductors.
An outstanding question, however, is whether the microscopic electronic model
for these systems -- the multi-orbital Hubbard model -- displays such an
ordered state a... | 1510.01389v2 |
2015-10-08 | Orbital order, spin waves, and doping effects in the $(π,0)$ SDW state --- comparative study of the three band models for iron pnictides | Aimed at identifying the role of microscopic Hamiltonian parameters on spin
wave excitations, orbital order, and magnetic moments in the $(\pi,0)$ SDW
state, two different three band models for iron pnictides are compared --- one
at two-third filling ($n=4$) and another at half filling $(n=3)$ --- both of
which yield q... | 1510.02276v1 |
2015-10-23 | Charge doping versus impurity scattering in chemically substituted iron-pnictides | To reveal the relative importance of charge doping and defect scattering in
substitutionally modified 122 iron pnictides, we perform a systematic first
principles study on selected bands at the Fermi level. Disorder effects are
induced by various substitutions using an orbital based coherent potential
approximation (CP... | 1510.06941v1 |
2015-10-29 | Robust Majorana signature detection with a coupled quantum dot-nanomechanical resonator in all-optical domain | Motivated by a recent experiment [Nadj-Perge et al., Science 346, 602 (2014)]
providing evidence for Majorana zero modes in iron chains on the
superconducting Pb surface, in the present work, we theoretically propose an
all-optical scheme to detect Majorana fermions, which is very different from
the current tunneling m... | 1510.08679v1 |
2015-11-03 | Doping-Enhanced Antiferromagnetism in Ca1-xLaxFeAs2 | In iron pnictides, high temperature superconductivity emerges after
suppressing antiferromagnetism by doping. Here we show that antiferromagnetism
in Ca$_{1-x}$La$_x$FeAs$_2$ is robust against and even enhanced by doping.
Using $^{75}$As-nuclear magnetic resonance and nuclear quadrupole resonance
techniques, we find th... | 1511.00760v1 |
2015-11-03 | The role of spin-orbit interaction in the ultrafast demagnetization of small iron clusters | The ultra-fast demagnetization of small iron clusters initiated by an intense
optical excitation is studied with time-dependent spin density functional
theory (TDSDFT). In particular we investigate the effect of the spin-orbit
interaction on the onset of the demagnetization process. It is found that the
initial rate of... | 1511.00864v1 |
2015-11-09 | Energy dependence of the spin excitation anisotropy in uniaxial-strained BaFe1.9Ni0.1As2 | We use inelastic neutron scattering to study the temperature and energy
dependence of the spin excitation anisotropy in uniaxial-strained
electron-doped iron pnictide BaFe$_{1.9}$Ni$_{0.1}$As$_2$ near optimal
superconductivity ($T_c=20$ K). Our work has been motivated by the observation
of in-plane resistivity anisotro... | 1511.02759v1 |
2015-12-07 | Origin of the DC and AC conductivity anisotropy in iron-based superconductors: scattering rate versus spectral weight effects | To shed light on the mechanism responsible for the in-plane resistivity
anisotropy in the nematic phase of the iron-based superconductors, we
investigate the impact of spin fluctuations on the anisotropic AC conductivity.
On the one hand, the scattering of electrons off magnetic fluctuations causes
an anisotropic scatt... | 1512.02259v2 |
2015-12-08 | Multi-orbital quantum antiferromagnetism in iron pnictides --- effective spin couplings and quantum corrections to sublattice magnetization | Towards understanding the multi-orbital quantum antiferromagnetism in iron
pnictides, effective spin couplings and spin fluctuation induced quantum
corrections to sublattice magnetization are obtained in the $(\pi,0)$ AF state
of a realistic three band interacting electron model involving $xz$, $yz$, and
$xy$ Fe 3d orb... | 1512.02398v1 |
2015-12-15 | Elastic coupling and spin-driven nematicity in iron-based superconductors | Spin-driven nematic order that has been proposed for iron-based
superconductors is generated by pronounced fluctuations of a striped density
wave state. On the other hand it is a well known fact that nematic order
parameter couples bilinearly to the strain, which supresses the fluctuations of
the nematic order paramete... | 1512.04861v1 |
2015-12-28 | Hole-$s_{\pm}$ State Induced by Coexisting Ferro- and Aniferromagnetic and Aniferro-orbital Fluctuations in the Iron Pnictides | The multi-orbital Hubbard model is investigated in order to clarify the
electron correlation effects and the superconductivity in the iron-based
superconductor. The renormalization effects on the self-energy and the
two-particle irreducible vertex function are calculated on the basis of the
dynamical mean field theory.... | 1512.08327v1 |
2016-01-08 | Detecting the orbital character of the spin fluctuation in the Iron-based superconductors with the resonant inelastic X-ray scattering spectroscopy | The orbital distribution of the spin fluctuation in the iron-based
superconductors(IBSs) is the key information needed to understand the
magnetism, superconductivity and electronic nematicity in these multi-orbital
systems. In this work, we propose that the resonant inelastic X-ray
scattering(RIXS) technique can be use... | 1601.01809v3 |
2016-01-12 | The B/C and sub-Iron/Iron Cosmic ray ratios - further evidence in favor of the spiral arm diffusion model | The Boron to Carbon (B/C) and sub-Fe/Fe ratios provides an important clue on
Cosmic Ray (CR) propagation within the Galaxy. These ratios estimate the
grammage that the CR traverse as they propagate from their sources to Earth.
Attempts to explain these ratios within the standard CR propagation models
require ad hoc mod... | 1601.03072v2 |
2016-01-13 | Relationship between Pairing Symmetries and Interaction Parameters in Iron-Based Superconductors from Functional Renormalization Group Calculations | Pairing symmetries of iron-based superconductors are investigated
systematically in a five-orbital model within the different regions of
interaction parameters by functional renormalization group(FRG). Even for a
fixed Fermi surface with both hole and electron pockets, it is found that
depending on interaction paramete... | 1601.03228v2 |
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