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2011-02-09 | Iron vacancy superstructure and possible room temperature antiferromagnetic order in superconducting Cs_{y}Fe_{2-x}Se_2 | Neutron and x-ray powder and single crystal synchrotron diffraction of
CsyFe2-xSe2 show the presence of superstructure reflections with propagation
vector k=[2/5, 1/5, 1] with respect to the average crystal structure I4/mmm (a
= 4, c = 15A). The propagation vector star corresponds to the 5 times bigger
unit cell given ... | 1102.1919v2 |
2011-02-11 | Quasiparticle states around a nonmagnetic impurity in electron-doped iron-based superconductors with spin-density-wave order | The quasiparticle states around a nonmagnetic impurity in electron-doped
iron-based superconductors with spin-density-wave (SDW) order are investigated
as a function of doping and impurity scattering strength. In the undoped
sample, where a pure SDW state exists, two impurity-induced resonance peaks are
observed around... | 1102.2401v1 |
2011-02-16 | Room temperature antiferromagnetic order in superconducting X_yFe_{2-x}Se_ 2, (X= Rb, K): a powder neutron diffraction study | Magnetic and crystal structures of superconducting X yFe 2-xSe 2 (X= Rb and K
with Tc=31.5 K and 29.5 K) have been studied by neutron powder diffraction at
room temperature. Both crystals show ordered iron vacancy pattern and the
crystal structure is well described in the I4/m space group with the lattice
constants a=8... | 1102.3380v1 |
2011-03-05 | Orbital magnetic response and the anisotropy of magnetic susceptibility in the Iron-based superconductors | We propose that the orbital angular momentum of the conduction electrons in
the Iron-based superconductors is activated in their low energy physics. Using
a five-band tight-binding model derived from fitting the LDA band structure, we
find that the orbital magnetic susceptibility of the conduction electrons in
such a m... | 1103.1056v2 |
2011-03-10 | Weighing Super-Massive Black Holes with Narrow Fe K$α$ Line | It has been suggested that the narrow cores of the Fe K$\alpha$ emission
lines in Active Galactic Nuclei (AGNs) are likely produced in the torus, the
inner radius of which can be measured by observing the lag time between the $V$
and $K$ band flux variations. In this paper we compare the virial products of
the infrared... | 1103.1927v2 |
2011-03-14 | AGN feedback and iron enrichment in the powerful radio galaxy, 4C+55.16 | We present a detailed X-ray analysis of 4C+55.16, an unusual and interesting
radio galaxy, located at the centre of a cool core cluster of galaxies.
4C+55.16 is X-ray bright (L(cluster)~10^45 erg/s), radio powerful, and shows
clear signs of interaction with the surrounding intracluster medium. By
combining deep Chandra... | 1103.2585v2 |
2011-03-16 | Superconductivity at the Border of Electron Localization and Itinerancy | The superconducting state of iron pnictides and chalcogenides exists at the
border of antiferromagnetic order. Consequently, these materials could provide
clues about the relationship between magnetism and unconventional
superconductivity. One explanation, motivated by the so-called bad-metal
behaviour of these materia... | 1103.3259v2 |
2011-03-17 | Origin of Orthorhombic Transition, Magnetic Transition, and Shear Modulus Softening in Iron Pnictide Superconductors: Analysis based on the Orbital Fluctuation Theory | The main features in iron-pnictide superconductors are summarized as (i) the
orthorhombic transition accompanied by remarkable softening of shear modulus,
(ii) high-Tc superconductivity close to the orthorhombic phase, and (iii)
stripe-type magnetic order induced by orthorhombicity. To present a unified
explanation for... | 1103.3360v3 |
2011-03-25 | Unconventional temperature enhanced magnetism in iron telluride | Highly energetic magnetic fluctuations, discovered in high-temperature
superconductors (HTSC) by inelastic neutron scattering (INS), are now widely
believed to be vital for the superconductivity. In two competing scenarios,
they either originate from local atomic spins, or are a property of cooperative
spin-density-wav... | 1103.5073v1 |
2011-04-12 | Isotropic three-dimensional gap in the iron-arsenide superconductor LiFeAs from directional heat transport measurements | The thermal conductivity k of the iron-arsenide superconductor LiFeAs (Tc ~
18K) was measured in single crystals at temperatures down to T~50mK and in
magnetic fields up to H=17T, very close to the upper critical field Hc2~18T.
For both directions of the heat current, parallel and perpendicular to the
tetragonal c-axis... | 1104.2209v2 |
2011-05-06 | Effect of iron content and potassium substitution in A$_{0.8}$Fe$_{1.6}$Se$_2$ (A = K, Rb, Tl) superconductors: a Raman-scattering investigation | We have performed Raman-scattering measurements on high-quality single
crystals of the superconductors K$_{0.8}$Fe$_{1.6}$Se$_2$ ($T_c$ = 32 K),
Tl$_{0.5}$K$_{0.3}$Fe$_{1.6}$Se$_2$ ($T_c$ = 29 K), and
Tl$_{0.5}$Rb$_{0.3}$Fe$_{1.6}$Se$_2$ ($T_c$ = 31 K), as well as of the
insulating compound KFe$_{1.5}$Se$_2$. To interp... | 1105.1198v2 |
2011-05-10 | Magnetic-crystallographic phase diagram of superconducting parent compound Fe$_{1+x}$Te | hrough neutron diffraction experiments, including spin-polarized
measurements, we find a collinear incommensurate spin-density wave with
propagation vector $ \mathbf k = $ ($0.4481(4) \, \,0 \, \, \frac1 2$) at base
temperature in the superconducting parent compound Fe$_{1+x}$Te. This critical
concentration of intersti... | 1105.1937v1 |
2011-05-20 | Orbital-Selective Superconductivity and the Effect of Lattice Distortion in Iron-Based Superconductors | The superconducting (SC) state of iron-based compounds in both tetragonal and
orthorhombic phases is studied on the basis of an effective Hamiltonian
composed of the kinetic energy including the five Fe 3d-orbitals, the
orthorhombic crystalline electric field (CEF) energy, and the two-orbital
Kugel'-Khomski\u{i}-type s... | 1105.4028v1 |
2011-06-10 | Electron doped Ca10(Pt3As8)(Fe2As2)5 and Ca10(Pt4As8)(Fe2As2)5 - High Tc superconductors with skutterudite intermediary layers | It has been argued that the very high transition temperatures of the highest
Tc cuprate superconductors are facilitated by enhanced CuO2 plane coupling
through the (Bi,Tl,Hg)-O intermediary layers. Whether enhanced coupling through
intermediary layers can also influence Tc in the iron arsenide superconductors
has never... | 1106.2111v1 |
2011-06-12 | Upper critical field and thermally activated flux flow in single crystalline Tl$_{0.58}$Rb$_{0.42}$Fe$_{1.72}$Se$_2$ | The upper critical field $\mu_0H_{c2}(T_c)$ of
Tl$_{0.58}$Rb$_{0.42}$Fe$_{1.72}$Se$_2$ single crystals has been determined by
means of measuring the electrical resistivity in both a pulsed magnetic field
($\sim$60T) and a DC magnetic field ($\sim$14T). It is found that $H_{c2}$
linearly increases with decreasing temper... | 1106.2283v2 |
2011-06-16 | Modulated superconductivity due to vacancy and magnetic order in $A_x$Fe$_{2-x/2}$Se$_2$ [$A=$Cs, K, (Tl,Rb), (Tl,K)] iron-selenide superconductors | We present a calculation of a 'modulated' superconducting state in
iron-selenide superconductors. The zero-momentum $d-$wave pairing breaks the
translational symmetry of the conventional BaFe$_2$Se$_2$-like crystal of
$I4/mmm$ space group. This pairing state becomes compatible when the Fe
vacancies form an ordered stat... | 1106.3289v1 |
2011-07-04 | Comparative studies of the scanning tunneling spectra in cuprate and iron-arsenide superconductors | We report scanning tunneling spectroscopic studies of cuprate and
iron-arsenic superconductors, including YBa_2Cu_3O_{7-\delta} (Y-123, T_c = 93
K), Sr_{0.9}La_{0.1}CuO_2 (La-112, T_c = 43 K), and the "122" compounds
Ba(Fe_{1-x}Co_x)_2As_2 (Co-122 with x = 0.06, 0.08, 0.12 for T_c = 14, 24, 20
K). For H > 0, pseudogap ... | 1107.0697v1 |
2011-08-19 | Structure and magnetic properties of nanostructured Pd-Fe thin films produced by pulse electrodeposition | Nanostructured Pd-Fe thin films with varied Fe content were prepared by
electrodeposition technique from organic electrolytes on Cu and brass
substrates. The structure and the magnetic properties of the films were
investigated prior to post-deposition annealing. The structure of the Pd1-xFex
thin films with x = 0.14, 0... | 1108.3888v1 |
2011-09-07 | Solar Cycle Variations in the Elemental Abundance of Helium and Fractionation of Iron in the Fast Solar Wind - Indicators of an Evolving Energetic Release of Mass from the Lower Solar Atmosphere | We present and discuss the strong correspondence between evolution of the
emission length scale in the lower transition region and in situ measurements
of the fast solar wind composition during this most recent solar minimum. We
combine recent analyses demonstrating the variance in the (supergranular)
network emission ... | 1109.1408v1 |
2011-09-22 | Self-Diffusion of Iron in L10 FePd films Upon He-irradiation (alternative title: An alternative for diffusion studies in isotopic FePd multilayers) | The continuous need towards improving the capacity of magnetic storage
devices requires materials with strong perpendicular magnetic anisotropy. FePd,
CoPd and their Co(Fe)Pt counterparts very attractive candidate for such
purposes. The magnetic properties of these films are largely dependent on the
orientation and loc... | 1109.4742v1 |
2011-10-26 | Non-Fermi Liquid due to Orbital Fluctuations in Iron Pnictide Superconductors | We study the influence of quantum fluctuations on the electron self energy in
the normal state of iron-pnictide superconductors using a five orbital tight
binding model with generalized Hubbard on-site interactions. Within a one-loop
treatment, we find that an overdamped collective mode develops at low frequency
in cha... | 1110.5917v4 |
2011-10-27 | Analysing the Suzaku Spectra of the Broad-Line Seyfert 1 Galaxy CBS 126 | We analysed new simultaneous \emph{Suzaku} and \emph{Swift} data of the Broad
Line Seyfert 1 (BLS1) galaxy CBS 126. A clear Fe emission line and a strong
soft excess are present in the source spectra. We fit the spectra with a
relativistic reflection model and find the model tends to fit the data with a
high iron abund... | 1110.6047v2 |
2011-12-01 | Observational studies of Cepheid amplitudes. II Metallicity dependence of pulsation amplitudes | Physical and phenomenological properties (radius, luminosity, shape of the
light curve, etc.) of Cepheids strongly depend on the pulsation period, with
the exception of the pulsation amplitude. A possible factor causing a wide
range of pulsation amplitudes might be the different atmospheric metallicities
of individual ... | 1112.0115v1 |
2012-01-25 | Newly-born pulsars as sources of ultrahigh energy cosmic rays | Newly-born pulsars offer favorable sites for the injection of heavy nuclei,
and for their further acceleration to ultrahigh energies. Once accelerated in
the pulsar wind, nuclei have to escape from the surrounding supernova envelope.
We examine this escape analytically and numerically, and discuss the pulsar
source sce... | 1201.5197v1 |
2012-02-28 | U(1) Slave-spin theory and its application to Mott transition in a multi-orbital model for iron pnictides | A U(1) slave-spin representation is introduced for multi-orbital Hubbard
models. As with the $Z_2$ form of L. de'Medici et al. (Phys. Rev. B 72, 205124
(2005)), this approach represents a physical electron operator as the product
of a slave spin and an auxiliary fermion operator. For non-degenerate
multi-orbital models... | 1202.6115v1 |
2012-02-29 | The s-process nucleosynthesis in massive stars: current status and uncertainties due to convective overshooting | Context: It is well known that the so-called s-process is responsible for the
production of neutron-rich trans-iron elements, that form the bulk of the
"heavy nuclides" (i.e. nuclides more massive than the iron-group nuclei) in the
solar-system composition, considered as "standard of reference" dataset for
cosmic abund... | 1202.6577v2 |
2012-03-20 | Orbital fluctuation theory in iron-based superconductors: s-wave superconductivity, structure transition, and impurity-induced nematic order | The main features in iron-based superconductors would be (i) the orthorhombic
transition accompanied by remarkable softening of shear modulus, (ii) high-Tc
superconductivity close to the orthorhombic phase, and (iii) nematic transition
in the tetragonal phase. In this paper, we present a unified explanation for
them, b... | 1203.4602v2 |
2012-03-22 | Magnetic hour-glass dispersion and its relation to high-temperature superconductivity in iron-tuned Fe$_{1+y}$Te$_{0.7}$Se$_{0.3}$ | High-temperature superconductivity remains arguably the largest outstanding
enigma of condensed matter physics. The discovery of iron-based
high-temperature superconductors has renewed the importance of understanding
superconductivity in materials susceptible to magnetic order and fluctuations.
Intriguingly they show m... | 1203.4974v2 |
2012-03-28 | Geometric and disorder -- type magnetic frustration in ferrimagnetic "114" Ferrites: Role of diamagnetic Li+ and Zn2+ cation substitution | The comparative study of the substitution of zinc and lithium for iron in the
"114" ferrites, YBaFe4O7 and CaBaFe4O7, shows that these diamagnetic cations
play a major role in tuning the competition between ferrimagnetism and magnetic
frustration in these oxides. The substitution of Li or Zn for Fe in the cubic
phase Y... | 1203.6220v1 |
2012-04-17 | Manifestations of nematic degrees of freedom in the magnetic, elastic, and superconducting properties of the iron pnictides | We investigate how emergent nematic order and nematic fluctuations affect
several macroscopic properties of both the normal and superconducting states of
the iron pnictides. Due to its magnetic origin, long-range nematic order
enhances magnetic fluctuations, leaving distinctive signatures in the
spin-lattice relaxation... | 1204.3694v3 |
2012-04-19 | Evolution from unconventional spin density wave to superconductivity and a novel gap-like phase in NaFe1-xCoxAs | Similar to the cuprate high TC superconductors, the iron pnictide
superconductors also lie in close proximity to a magnetically ordered phase. A
central debate concerning the superconducting mechanism is whether the local
magnetic moments play an indispensable role or the itinerant electron
description is sufficient. A... | 1204.4237v1 |
2012-04-25 | Fermi surface evolution and checker-board block-spin antiferromagnetism in $A_x$Fe$_{2-y}$Se$_{2}$ | We develop an effective multiorbital mean-field t-J Hamiltonian with
realistic tight-binding and exchange parameters to describe the electronic and
magnetic structures of iron-selenide based superconductors
$A_x$Fe$_{2-y}$Se$_2$ for iron vacancy doping in the range $0 \leq y \leq 0.4$.
The Fermi surface topology extrac... | 1204.5768v1 |
2012-05-01 | Shielding Experiments Under JASMIN Collaboration at Fermilab(III) - Measurement of High-Energy Neutrons Penetrating a Thick Iron Shield from the Antiproton Production Target by AU Activation Method | In an antiproton production (Pbar) target station of the Fermi National
Accelerator Laboratory (FNAL), the secondary particles produced by bombarding a
target with 120-GeV protons are shielded by a thick iron shield. In order to
obtain experimental data on high-energy neutron transport at more than
100-GeV-proton accel... | 1205.0265v1 |
2012-05-15 | Magnetic States of the Two-Leg Ladder Alkali Metal Iron Selenides $A$Fe$_2$Se$_3$ | Recent neutron scattering experiments addressing the magnetic state of the
two-leg ladder selenide compound BaFe$_2$Se$_3$ have unveiled a dominant spin
arrangement involving ferromagnetically ordered 2$\times$2 iron-superblocks,
that are antiferromagnetically coupled among them (the "block-AFM" state).
Using the elect... | 1205.3239v3 |
2012-06-06 | The role of oxygen vacancies on the structure and the density of states of iron doped zirconia | In this paper we study, both with theoretical and experimental approach, the
effect of iron doping in zirconia. Combining density functional theory (DFT)
simulations with the experimental characterization of thin films, we show that
iron is in the Fe3+ oxidation state and accordingly that the films are rich in
oxygen v... | 1206.1197v4 |
2012-06-07 | Effect of inelastic scattering on the nuclear magnetic relaxation rate 1/T1T in iron-based superconductors | We present a microscopic study of the nuclear magnetic relaxation rate 1/T1
based on the five-orbital model for iron-based superconductors. We mainly
discuss the effect of the "inelastic" quasi-particle damping rate {\gamma} due
to many-body interaction on the size of the coherence peak, for both s++ and
s+- wave super... | 1206.1399v2 |
2012-06-11 | Metastable superconducting state in quenched KxFe2-ySe2 | By direct quenching or post-annealing followed by quenching, we have
successfully obtained a series of KxFe2-ySe2 samples with different properties.
It is found that the samples directly quenched in the cooling process of growth
show superconductivity and the one cooled with furnace is insulating even
though their stoi... | 1206.2191v1 |
2012-08-08 | Composition Structure of Interplanetary Coronal Mass Ejections From Multispacecraft Observations, Modeling, and Comparison with Numerical Simulations | We present an analysis of the ionic composition of iron for two
interplanetary coronal mass ejections observed in May 21-23 2007 by the ACE and
STEREO spacecraft in the context of the magnetic structure of the ejecta flux
rope, sheath region, and surrounding solar wind flow. This analysis is made
possible due to recent... | 1208.1791v3 |
2012-08-31 | Radiative properties of magnetic neutron stars with metallic surfaces and thin atmospheres | The goal of this work is to develop a simple analytic description of the
emission properties (spectrum and polarization) of the condensed, strongly
magnetized surface of neutron stars. We have improved the method of van
Adelsberg et al. (2005) (arXiv:astro-ph/0406001) for calculating the spectral
properties of condense... | 1208.6582v2 |
2012-09-18 | Active galaxy 4U 1344-60: did the relativistic line disappear? | X-ray bright active galactic nuclei represent a unique astrophysical
laboratory for studying accretion physics around super-massive black holes. 4U
1344-60 is a bright Seyfert galaxy which revealed relativistic reflection
features in the archival XMM-Newton observation. We present the spectroscopic
results of new data ... | 1209.4068v1 |
2012-10-05 | Rapid Size-Controlled Synthesis of Dextran-Coated, 64Cu-Doped Iron Oxide Nanoparticles | Research into developing dual modality probes enabled for magnetic resonance
imaging (MRI) and positron emission tomography (PET) has been on the rise
recently due to the potential to combine the high resolution of MRI and the
high sensitivity of PET. Current synthesis techniques for developing multimodal
probes is lar... | 1210.1823v1 |
2012-10-18 | Specific Heat vs Field of LiFe1-xCuxAs | LiFeAs is one of the new class of iron superconductors with a bulk onset Tc
in the 15-17 K range. We report on the specific heat characterization of single
crystal material prepared from self-flux growth techniques with significantly
improved properties, including a much decreased residual gamma (proportional to
C/T as... | 1210.4995v1 |
2012-11-12 | Testing the space-time geometry around black hole candidates with the analysis of the broad K$α$ iron line | Astrophysical black hole candidates are thought to be the Kerr black holes
predicted by General Relativity, but there is not yet clear evidence that the
geometry of the space-time around these objects is really described by the Kerr
metric. In order to confirm the Kerr black hole hypothesis, we have to observe
strong g... | 1211.2513v2 |
2012-12-19 | Emergent Nesting of the Fermi Surface from Local-Moment Description of Iron-Pnictide High-Tc Superconductors | We uncover the low-energy spectrum of a t-J model for electrons on a square
lattice of spin-1 iron atoms with 3dxz and 3dyz orbital character by applying
Schwinger-boson-slave-fermion mean-field theory and by exact diagonalization of
one hole roaming over a 4 x 4 x 2 lattice. Hopping matrix elements are set to
produce ... | 1212.4619v3 |
2012-12-20 | Measurement of Coherent Polarons in the Strongly Coupled Antiferromagnetically Ordered Iron-Chalcogenide Fe1.02Te using Angle-Resolved Photoemission Spectroscopy | The nature of metallicity and the level of electronic correlations in the
antiferromagnetically ordered parent compounds are two important open issues
for the iron-based superconductivity. We perform a temperature-dependent
angle-resolved photoemission spectroscopy study of Fe1.02Te, the parent
compound for iron chalco... | 1212.4946v1 |
2013-03-02 | Signs of atmospheric inhomogeneities in cool stars from 1D-NLTE analysis of iron lines | For the well studied halo star HD 122563 and the four stars in the globular
cluster NGC 6397, we determine NLTE abundances of iron using classical
plane-parallel model atmospheres. Each star reveals a discrepancy in abundances
between the Fe I lines arising from the ground state and the other Fe I lines,
in qualitative... | 1303.0357v1 |
2013-03-04 | Orbital selective correlations between nesting/scattering/Lifshitz transition and the superconductivity in AFe1-xCoxAs (A=Li, Na) | The correlations between the superconductivity in iron pnictides and their
electronic structures are elusive and controversial so far. Here through
angle-resolved photoemission spectroscopy measurements, we show that such
correlations are rather distinct in AFe$_{1-x}$Co$_x$As (A=Li, Na), but only
after one realizes th... | 1303.0682v2 |
2013-03-11 | Magnetically-Driven Suppression of Nematic Order in an Iron-Based Superconductor | A theory of superconductivity in the iron-based materials requires an
understanding of the phase diagram of the normal state. In these compounds,
superconductivity emerges when stripe spin density wave (SDW) order is
suppressed by doping, pressure or atomic disorder. This magnetic order is often
pre-empted by nematic o... | 1303.2647v2 |
2013-03-12 | Change of pairing symmetry in the iron-based superconductor KFe2As2 | The pairing mechanism in iron-based superconductors is the subject of ongoing
debate. Proximity to an antiferromagnetic phase suggests that pairing is
mediated by spin fluctuations, but orbital fluctuations have also been invoked.
The former typically favour a pairing state of extended s-wave symmetry with a
gap that c... | 1303.2961v3 |
2013-04-11 | Sign-reversal of the in-plane resistivity anisotropy in iron pnictides | The concept of an electronically-driven breaking of the rotational symmetry
of a crystal, without involving magnetic order, has found experimental support
in several systems, from semiconductor heterostructures and ruthenates, to
cuprate and iron-pnictide superconductors. In the pnictide BaFe$_{2}$As$_{2}$,
such an "el... | 1304.3490v1 |
2013-04-12 | Space group symmetry, spin-orbit coupling and the low energy effective Hamiltonian for iron based superconductors | We construct the symmetry adapted low energy effective Hamiltonian for the
electronic states in the vicinity of the Fermi level in iron based
superconductors. We use Luttinger's method of invariants, expanding about Gamma
and M points in the Brillouin zone corresponding to two iron unit cell, and
then matching the coef... | 1304.3723v1 |
2013-05-23 | Measuring the Kerr spin parameter of a non-Kerr compact object with the continuum-fitting and the iron line methods | Under the assumption that astrophysical black hole candidates are the Kerr
black holes of general relativity, the continuum-fitting method and the
analysis of the K$\alpha$ iron line are today the only available techniques
capable of providing a relatively reliable estimate of the spin parameter of
these objects. If we... | 1305.5409v2 |
2013-06-05 | BeppoSAX and XMM-Newton spectral study of 4U 1735-44 | Low-mass X-ray binary systems consist of a neutron star and a main-sequence
companion star. The compact object accretes matter via Roche-lobe overflow,
which leads to an accretion disk. In addition to a broad-band continuum
emission of a thermal component and a Comptonization part, evidence for a broad
iron K{\alpha} l... | 1306.1040v1 |
2013-06-22 | A Toroidal Magnetised Iron Neutrino Detector (MIND) for a Neutrino Factory | A neutrino factory has unparalleled physics reach for the discovery and
measurement of CP violation in the neutrino sector. A far detector for a
neutrino factory must have good charge identification with excellent background
rejection and a large mass. An elegant solution is to construct a magnetized
iron neutrino dete... | 1306.5327v2 |
2013-07-18 | Steady state rheological behaviour of multi-component magnetic suspensions | In this paper we study the rheological behaviour (in the absence of magnetic
field and upon its application) of multi-component magnetic suspensions that
consist of a mixture of magnetic (iron) and non-magnetic (PMMA) particles
dispersed in a liquid carrier. These suspensions exhibit considerably higher
viscosity and y... | 1307.4975v1 |
2013-08-05 | Physics picture from neutron scattering study on Fe-based superconductors | Neutron scattering, with its ability to measure the crystal structure, the
magnetic order, and the structural and magnetic excitations, plays an active
role in investigating various families of Fe-based high-Tc superconductors.
Three different types of antiferromag- netic orders have been discovered in the
Fe plane, bu... | 1308.1040v1 |
2013-08-28 | Strong electronic correlations in iron pnictides: Comparison of the optical spectra for BaFe2As2-related compounds | We carried out combined transport and optical measurements for BaFe2As2 and
five isostructural transition-metal (TM) pnictides. The low-energy optical
conductivity spectra of these compounds are, to a good approximation,
decomposed into a narrow Drude (coherent) component and an incoherent
component. The iron arsenides... | 1308.6113v1 |
2013-09-06 | Investigation of the Puzzling Abundance Pattern in the Stars of the Fornax Dwarf Spheroidal Galaxy | Many works have found unusual characteristics of elemental abundances in
nearby dwarf galaxies. This implies that there is a key factor of galactic
evolution that is different from that of the Milky Way (MW). The chemical
abundances of the stars in the Fornax dwarf spheroidal galaxy (Fornax dSph)
provide excellent info... | 1309.1519v1 |
2013-10-04 | The soft component and the iron line as signatures of the disc inner radius in Galactic black hole binaries | The inner radius of the accretion disc around a black hole in the low/hard
state can be measured in one of two ways. Firstly, via the extent of broadening
of the iron emission line, and secondly, from the luminosity and temperature of
the weak soft component seen in this state, assuming it is the disc. We use
both of t... | 1310.1219v1 |
2013-11-14 | Electric field gradient wave (EFGW) in iron-based superconductor Ba(0.6)K(0.4)Fe2As2 studied by Mössbauer spectroscopy | The optimally doped 122 iron-based superconductor Ba(0.6)K(0.4)Fe2As2 has
been studied by 57Fe Moessbauer spectroscopy versus temperature ranging from
4.2 K till 300 K with particular attention paid to the superconducting
transition around 38 K. The spectra do not contain magnetic components and they
exhibit quasi-cont... | 1311.3503v4 |
2013-11-22 | A first-principles study of the electronic structure of Iron-Selenium; Implications for electron-phonon superconductivity | We have performed density functional theory (DFT) calculations using the
linearized augmented plane wave method (LAPW) with the local density
approximation (LDA) functional to study the electronic structure of the
iron-based superconductor Iron-Selenium (FeSe). In our study, we have performed
a comprehensive set of cal... | 1311.5914v2 |
2014-02-04 | Spin and orbital magnetic moments of size-selected iron, cobalt, and nickel clusters and their link to the bulk phase diagrams | Spin and orbital magnetic moments of cationic iron, cobalt, and nickel
clusters have been determined from x-ray magnetic circular dichroism
spectroscopy. In the size regime of $n = 10 - 15$ atoms, these clusters show
strong ferromagnetism with maximized spin magnetic moments of 1~$\mu_B$ per
empty $3d$ state because of... | 1402.0701v1 |
2014-02-07 | Modelling a new, low CO2 emissions, hydrogen steelmaking process | In an effort to develop breakthrough technologies that enable drastic
reduction in CO2 emissions from steel industry (ULCOS project), the reduction
of iron ore by pure hydrogen in a direct reduction shaft furnace was
investigated. After experimental and modelling studies, a 2D, axisymmetrical
steady-state model called ... | 1402.1715v1 |
2014-02-15 | Identifying the `Fingerprint' of Antiferromagnetic Spin-Fluctuations on Iron-Pnictide Superconductivity | Cooper pairing in the iron-based high-Tc superconductors is often conjectured
to involve bosonic fluctuations. Among the candidates are antiferromagnetic
spin-fluctuations and d-orbital fluctuations amplified by phonons. Any such
electron-boson interaction should alter the electron's `self-energy', and then
become dete... | 1402.3714v2 |
2014-02-17 | Pressure decoupled magnetic and structural transitions of the parent compound of iron based 122 superconductors BaFe2As2 | The recent discovery of iron ferropnictide superconductors has received
intensive concerns on magnetic involved superconductors. Prominent features of
ferropnictide superconductors are becoming apparent: the parent compounds
exhibit antiferromagnetic (AFM) ordered spin density wave (SDW) state; the
magnetic phase trans... | 1402.4086v1 |
2014-03-05 | The chemical composition of a regular halo globular cluster: NGC 5897 | We report for the first time on the chemical composition of the halo cluster
NGC 5897 (R=12.5 kpc), based on chemical abundance ratios for 27 alpha-,
iron-peak, and neutron-capture elements in seven red giants. From our
high-resolution, high signal-to-noise spectra obtained with the Magellan/MIKE
spectrograph, we find ... | 1403.1262v1 |
2014-03-14 | Spin-dependent conductivity of iron-based superconductors in a magnetic field | We report the results of a study of magnetic field features of electron
transport in heterojunctions with NS boundary inside iron-based
superconductors, represented by a binary phase of $\alpha$ - FeSe and
oxyarsenide pnictide LaO(F)FeAs. We used the ability of self magnetic field of
the transport current to partially ... | 1403.3549v1 |
2014-03-24 | Bipartite magnetic parent phases in the iron-oxypnictide superconductor | High-temperature (high-$T_{\rm c}$) superconductivity appears as a
consequence of the carrier-doping of an undoped parent compound exhibiting
antiferromagnetic order; thereby, ground-state properties of the parent
compound are closely relevant to the superconducting state. On the basis of the
concept, a spin-fluctuatio... | 1403.6021v1 |
2014-04-01 | Magnetic states of the five-orbital Hubbard model for one-dimensional iron-based superconductors | The magnetic phase diagrams of models for quasi one-dimensional compounds
belonging to the iron-based superconductors family are presented. The
five-orbital Hubbard model and the real-space Hartree-Fock approximation are
employed, supplemented by density functional theory to obtain the hopping
amplitudes. Phase diagram... | 1404.0069v1 |
2014-04-01 | High-resolution abundance analysis of very metal-poor r-I stars | Moderately r-process-enriched stars (r-I) are at least four times as common
as those that are greatly enriched in r-process elements (r-II), and the
abundances in their atmospheres are important tools for obtaining a better
understanding of the nucleosynthesis processes responsible for the origin of
the elements beyond... | 1404.0234v1 |
2014-04-03 | Dynamics and mechanism of oxygen annealing in Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$ single crystal | Iron chalcogenide Fe(Te,Se) attracted much attention due to its simple
structure, which is favorable for probing the superconducting mechanism. Its
less toxic nature compared with iron arsenides is also advantageous for
applications of iron-based superconductors. By intercalating spacer layers,
superconducting transiti... | 1404.0916v1 |
2014-04-10 | Space weathering simulations through controlled growth of iron nanoparticles on olivine | Airless planetary bodies are directly exposed to space weathering. The main
spectral effects of space weathering are darkening, reduction in intensity of
silicate mineral absorption bands, and an increase in the spectral slope
towards longer wavelengths (reddening). Production of nanophase metallic iron
(npFe$^{0}$) du... | 1404.2956v2 |
2014-07-02 | Connection between ambient-pressure and pressure-induced superconducting phases in alkaline iron selenide superconductors | A unique platform for investigating the correlation between the
antiferromagnetic (AFM) and superconducting (SC) states in high temperature
superconductors is created by the discovery of alkaline iron selenide
superconductors which are composed of an AFM insulating phase and a SC phase
separated spatially. Our previous... | 1407.0589v2 |
2014-07-24 | Preventing corona effects: multi-phosphonic acid poly(ethylene glycol) copolymers for stable stealth iron oxide nanoparticles | When disperse in biological fluids, engineered nanoparticles are selectively
coated with proteins, resulting in the formation of a protein corona. It is
suggested that the protein corona is critical in regulating the conditions of
entry into the cytoplasm of living cells. Recent reports describe this
phenomenon as ubiq... | 1407.6411v1 |
2014-08-05 | Two spatially separated phases in semiconducting Rb$_{0.8}$Fe$_{1.5}$S$_2$ | We report neutron scattering and transport measurements on semiconducting
Rb$_{0.8}$Fe$_{1.5}$S$_2$, a compound isostructural and isoelectronic to the
well-studied $A_{0.8}$Fe$_{y}$Se$_2 (A=$ K, Rb, Cs, Tl/K) superconducting
systems. Both resistivity and DC susceptibility measurements reveal a magnetic
phase transition... | 1408.0842v1 |
2014-08-10 | Unfolding of the electronic structure through the induced representations of space groups: Application to Fe-based superconductors | We revisit the problem that relevant parts of bandstructures for a given cell
choice can reflect exact or approximate higher symmetries of subsystems in the
cell and can therefore be significantly simplified by an unfolding procedure
that recovers the higher symmetry. We show that bandstructure unfolding can be
underst... | 1408.2258v2 |
2014-08-19 | Neutrino and anti-neutrino energy loss rates due to iron isotopes suitable for core-collapse simulations | Accurate estimate of neutrino energy loss rates are needed for the study of
the late stages of the stellar evolution, in particular for cooling of neutron
stars and white dwarfs. The energy spectra of neutrinos and antineutrinos
arriving at the Earth can also provide useful information on the primary
neutrino fluxes as... | 1408.4321v1 |
2014-08-19 | Stellar $β^{\pm}$ decay rates of iron isotopes and its implications in astrophysics | $\beta$-decay and positron decay are believed to play a consequential role
during the late phases of stellar evolution of a massive star culminating in a
supernova explosion. Recently the microscopic calculation of weak-interaction
mediated rates on key isotopes of iron was introduced using the proton-neutron
quasipart... | 1408.4407v1 |
2014-09-10 | Interpretation of the X-ray Spectral Variation of 1H0707-495 with a Variable Double Partial Covering Model | The Narrow-line Seyfert 1 galaxy 1H0707-495 is known to exhibit significant
X-ray spectral variations. Its X-ray energy spectrum is characterized by a
strong soft excess emission, an extremely deep iron K-edge structure at ~7 keV,
and a putative iron L-line/edge feature at ~1 keV. We have found that the
energy spectrum... | 1409.3019v1 |
2014-09-14 | Correlation-induced self-doping in intercalated iron-pnictide superconductor Ba2Ti2Fe2As4O | The electronic structure of the intercalated iron-based superconductor
Ba2Ti2Fe2As4O (Tc - 21.5 K) has been investigated by using angle-resolved
photoemission spectroscopy and combined local density approximation and
dynamical mean field theory calculations. The electronic states near the Fermi
level are dominated by b... | 1409.4090v1 |
2014-09-29 | MD Simulations of Compression of Nanoscale Iron Pillars | It is now possible to create perfect crystal nanowires of many metals. The
deformation of such objects requires a good understanding of the processes
involved in plasticity at the nanoscale. Isotropic compression of such
nanometre scale micropillars is a good model system to understand the
plasticity. Here we investiga... | 1409.8328v1 |
2014-10-14 | NLTE effects on AGB stars in 47 Tucanae | We present the iron abundance of 24 asymptotic giant branch (AGB) stars
members of the globular cluster 47 Tucanae, obtained with high-resolution
spectra collected with the FEROS spectrograph at the MPG/ESO-2.2m Telescope. We
find that the iron abundances derived from neutral lines (with mean value [Fe
I/H] = -0.94 +/-... | 1410.3841v1 |
2014-10-21 | A Study on the time resolution of Glass RPC | The 50~kton Iron Calorimeter (ICAL) detector at the underground India based
Neutrino Observatory (INO) will make measurements on atmospheric neutrinos.
Muons produced in charged current (CC) interactions of muon neutrinos with the
iron are tracked spatially and temporally through the signals that they produce
in the Re... | 1410.5532v1 |
2014-11-16 | Distinguishing spin-orbit coupling and nematic order in the electronic spectrum of iron-based superconductors | The low-energy electronic states of the iron-based superconductors are
strongly affected by both spin-orbit coupling and, when present, by the nematic
order. These two effects have different physical origins, yet they can lead to
similar gap features in the electronic spectrum. Here we show how to
disentangle them expe... | 1411.4303v1 |
2014-12-04 | High transport Jc in magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process | The recently discovered iron-based superconductors with very high upper
critical field and small anisotropy have been regarded as a potential candidate
material for high field applications. However, enhancements of superconducting
properties are still needed to boost the successful use of iron-based
superconductors in ... | 1412.1580v1 |
2014-12-12 | Magnetism of BaFe2Se3 studied by Mössbauer spectroscopy | The compound BaFe2Se3 (Pnma) has been synthesized in the form of single
crystals with the average composition Ba0.992Fe1.998Se3. The Moessbauer
spectroscopy used for investigation of the valence states of Fe in this
compound at temperature ranging from 4.2 K till room temperature revealed the
occurrence of mixed-valenc... | 1412.4024v2 |
2015-01-27 | The Compton hump and variable blue wing in the extreme low-flux NuSTAR observations of 1H0707-495 | The Narrow-line Seyfert I galaxy, 1H0707-495, has been well observed in the
0.3-10 keV band, revealing a dramatic drop in flux in the iron K alpha band, a
strong soft excess, and short timescale reverberation lags associated with
these spectral features. In this paper, we present the first results of a deep
250 ks NuST... | 1501.06849v2 |
2015-01-29 | Superconducting properties of sulfur-doped iron selenide | The recent discovery of high-temperature superconductivity in single-layer
iron selenide has generated significant experimental interest for optimizing
the superconducting properties of iron-based superconductors through the
lattice modification. For simulating the similar effect by changing the
chemical composition du... | 1501.07346v1 |
2015-02-25 | Crossover of the pairing symmetry from $s$- to $d$-wave in iron pnictide superconductors | One of the major themes in the physics of condensed matter is unconventional
superconductivity in correlated electronic systems. The symmetry structure of
Cooper pairs is thought to be the key to the understanding of the pairing
mechanism of their superconductivity. In iron pnictide superconductors, the
precise symmetr... | 1502.07130v1 |
2015-04-20 | A Mott insulator continuously connected to iron pnictide superconductors | Iron-based superconductivity develops near an antiferromagnetic order and out
of a bad metal normal state, which has been interpreted as originating from a
proximate Mott transition. Whether an actual Mott insulator can be realized in
the phase diagram of the iron pnictides remains an open question. Here we use
transpo... | 1504.05116v2 |
2015-04-26 | Manifestation of nematic degrees of freedom in the Raman response function of iron pnictides | We establish a relation between the Raman response function in the $B_{1g}$
channel and the electronic contribution to the nematic susceptibility within
the spin-driven approach to electron nematicity of the iron based
superconductors. The spin-driven nematic phase, characterized by the broken
$C_4$ symmetry, but unbro... | 1504.06841v2 |
2015-05-19 | Direct observation of a Fermi liquid-like normal state in an iron-pnictide superconductor | There are two prerequisites for understanding high-temperature (high-T$_c$)
superconductivity: identifying the pairing interaction and a correct
description of the normal state from which superconductivity emerges. The
nature of the normal state of iron-pnictide superconductors, and the role
played by correlations aris... | 1505.05139v1 |
2015-05-22 | Interaction-induced singular Fermi surface in a high-temperature oxypnictide superconductor | In the family of iron-based superconductors, LaFeAsO-type materials possess
the simplest electronic structure due to their pronounced two-dimensionality.
And yet they host superconductivity with the highest transition temperature
Tc=55K. Early theoretical predictions of their electronic structure revealed
multiple larg... | 1505.06152v1 |
2015-05-22 | Double-Q spin-density wave in iron arsenide superconductors | Elucidating the nature of the magnetic ground state of iron-based
superconductors is of paramount importance in unveiling the mechanism behind
their high temperature superconductivity. Until recently, it was thought that
superconductivity emerges only from an orthorhombic antiferromagnetic stripe
phase, which can in pr... | 1505.06175v1 |
2015-05-29 | Tables of phase functions, opacities, albedos, equilibrium temperatures, and radiative accelerations of dust grains in exoplanets | There has been growing observational evidence for the presence of condensates
in the atmospheres and/or comet-like tails of extrasolar planets. As a result,
systematic and homogeneous tables of dust properties are useful in order to
facilitate further observational and theoretical studies. In this paper we
present calc... | 1505.08013v2 |
2015-06-02 | Enhancement of the 6.4 keV line in the inner Galactic ridge: Proton-induced fluorescence? | A common idea for the origin of the Galactic diffuse X-ray emission,
particularly that of the iron lines from neutral and highly ionized atoms, is a
superposition of many cataclysmic variables and coronally active binaries. In
this scenario, the flux should symmetrically distribute between the east and
west on the plan... | 1506.00759v1 |
2015-06-02 | Localization and Orbital Selectivity in Iron-Based Superconductors with Cu Substitution | We study an inhomogeneous three-orbital Hubbard model for the Cu-substituted
iron pnictides using an extended real-space Green's function method combined
with density functional calculations. We find that the onsite interactions of
the Cu ions are the principal determinant of whether an electron dopant or a
hole dopant... | 1506.00767v3 |
2015-06-06 | Spectroscopic Studies of Quasiparticle Low-Energy Excitations in Cuprate and Iron-Based High-Temperature Superconductors | Recent development in the physics of high-temperature superconductivity is
reviewed, with special emphasis on the studies of the low-energy excitations of
cuprate and iron-based superconductors. For cuprate superconductors, a
phenomenology based on coexisting competing orders with superconductivity in
the ground state ... | 1506.02091v1 |
2015-06-09 | Better Alternative to "Astronomical Silicate": Laboratory-Based Optical Functions of Chondritic/Solar Abundance Glass With Application to HD161796 | "Astronomical" or "circumstellar" silicate optical functions (real and
imaginary indices of refraction n and k have been previously derived from
compositionally and structurally disparate samples; past values were compiled
from different sources in the literature, and are essentially kluges of
observational, laboratory... | 1506.03110v1 |
2015-06-18 | Unusual Sensitivity of Superconductivity to Strain in Iron-Based 122 Superconductors | Co-doped BaFe2As2 has been previously shown to have an unusually significant
improvement of Tc (up to 2 K, or almost 10%) with annealing 1-2 weeks at 700 or
800 C, where such annealing conditions are insufficient to allow significant
atomic diffusion. While confirming similar behavior in optimally Co-doped
SrFe2As2 sam... | 1506.05735v1 |
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