publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2006-01-30 | Iron self-diffusion in FeZr/$^{57}$FeZr multilayers measured by neutron reflectometry: Effect of applied compressive stress | Iron self-diffusion in nano-composite FeZr alloy has been investigated using
neutron reflectometry technique as a function of applied compressive stress. A
composite target of (Fe+Zr) and (57Fe+Zr) was alternatively sputtered to
deposit chemically homogeneous multilayer (CHM) structure,
[Fe75Zr25/57Fe75Zr25]10. The mul... | 0601646v1 |
2007-01-12 | Iron melting curve with a tricritical point | Solidification as a first order phase transition is described in the Landau
theory by the same equation as tricritical phenomena. Here, the solidification
or melting temperature against pressure curve is modelled to end at a
tricritical point. The model gives the phase transition temperature's
dependence on pressure up... | 0701283v1 |
2004-09-21 | The axial ratio of hcp iron at the conditions of the Earth's inner core | We present ab initio calculations of the high-temperature axial c/a ratio of
hexagonal-close-packed (hcp) iron at Earth's core pressures, in order to help
interpret the observed seismic anisotropy of the inner core. The calculations
are based on density functional theory, which is known to predict the
properties of hig... | 0409109v1 |
2007-10-29 | Muon content of ultra-high-energy air showers: Yakutsk data versus simulations | We analyse a sample of 33 extensive air showers (EAS) with estimated primary
energies above 2\cdot 10^{19} eV and high-quality muon data recorded by the
Yakutsk EAS array. We compare, event-by-event, the observed muon density to
that expected from CORSIKA simulations for primary protons and iron, using
SIBYLL and EPOS ... | 0710.5508v2 |
2007-11-03 | Inner-shell Annihilation of Positrons in Argon, Iron and Copper Atoms | The annihilation parameters of positrons with electrons in different shells
of Argon, Iron and Copper atoms are calculated below the positronium (Ps)
formation thresholds. Quite accurate ab initio calculations of the bound state
wavefunctions of Argon, Iron and Copper orbitals are obtained from Cowan
computer code. A l... | 0711.0453v1 |
2008-04-06 | Carbon nanotube-sharp tips and carbon nanotube-soldering irons | We report on the nano-electron beam assisted fabrication of atomically sharp
iron-based tips and on the creation of a nano-soldering iron for
nano-interconnects using Fe-filled multiwalled carbon nanotubes (MWCNTs). High
energy electron beam machining has been proven a powerful tool to modify
desired nanostructures for... | 0804.0929v1 |
2008-05-06 | Coherence-incoherence crossover in the normal state of iron-oxypnictides and importance of the Hund's rule coupling | A new class of high temperature superconductors based on iron and arsenic was
recently discovered, with superconducting transition temperature as high as 55
K. Here we show, using microscopic theory, that the normal state of the iron
pnictides at high temperatures is highly anomalous, displaying a Curie Weiss
susceptib... | 0805.0722v2 |
2008-05-27 | Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2 | The ternary iron arsenide BaFe2As2 with the tetragonal ThCr2Si2-type
structure exhibits a spin density wave (SDW) anomaly at 140 K, very similar to
LaFeAsO, the parent compound of the iron arsenide superconductors. BaFe2As2 is
a poor Pauli-paramagnetic metal and undergoes a structural and magnetic phase
transition at 1... | 0805.4021v2 |
2008-05-29 | Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2 | The ternary iron arsenide BaFe2As2 becomes superconducting by hole doping,
which was achieved by partial substitution of the barium site with potassium.
We have discovered bulk superconductivity up to Tc = 38 K in (Ba1-xKx)Fe2As2
with x = 0.4. The parent compound BaFe2As2 as well as KFe2As2 both crystallize
in the tetr... | 0805.4630v2 |
2008-06-04 | Parton distribution function uncertainties & nuclear corrections for the LHC | We study nuclear effects of charged current deep inelastic neutrino-iron
scattering in the framework of a chi^2 analysis of parton distribution
functions (PDFs). We extract a set of iron PDFs which are used to compute
x_Bj-dependent and Q^2-dependent nuclear correction factors for iron structure
functions which are req... | 0806.0723v1 |
2008-08-06 | Kondo Effect and Spin Glass Behavior of Dilute Iron Clusters in Silver Studied by Mössbauer Spectroscopy and Resistivity | Thin films of silver containing 0.3 - 1.5 at % Fe have been prepared by vapor
co-deposition. Depending on substrate temperature and iron concentration we
could systematically follow the formation of nanometer size clusters of iron
from initially dilute iron monomers. samples were characterized via X-ray
diffraction, re... | 0808.0929v1 |
2008-08-19 | Telescopes versus Microscopes: the puzzle of Iron-60 | The discovery that the short-lived radionucleide iron-60 was present in the
oldest meteorites suggests that the formation of the Earth closely followed the
death of a massive star. I discuss three astrophysical origins: winds from an
AGB star, injection of supernova ejecta into circumstellar disks, and induced
star for... | 0808.2506v1 |
2008-09-30 | Effect of the tetrahedral distortion on the electronic properties of iron-pnictides | We study the dependence of the electronic structure of iron pnictides on the
angle formed by the arsenic-iron bonds. Within a Slater-Koster tight binding
model which captures the correct symmetry properties of the bands, we show that
the density of states and the band structure are sensitive to the distortion of
the te... | 0810.0019v2 |
2008-10-13 | Synthesis, crystal structure and spin-density-wave anomaly of the iron arsenide-fluoride SrFeAsF | The new quaternary iron arsenide-fluoride SrFeAsF with the tetragonal
ZrCuSiAs-type structure was synthesized and the crystal structure was
determined by X-ray powder diffraction (P4/nmm, a = 399.30(1), c = 895.46(1)
pm). SrFeAsF undergoes a structural and magnetic phase transition at 175 K,
accompanied by strong anoma... | 0810.2120v1 |
2008-11-22 | A simple theory of the Invar effect in iron-nickel alloys | Certain alloys of iron and nickel (so-called 'Invar' alloys) exhibit almost
no thermal expansion over a wide range of temperature. It is clear that this is
the result of an anomalous contraction upon heating which counteracts the
normal thermal expansion arising from the anharmonicity of lattice vibrations.
This anomal... | 0811.3673v1 |
2008-12-17 | Nuclear Parton Distribution Functions | We study nuclear effects of charged current deep inelastic neutrino-iron
scattering in the framework of a chi^2 analysis of parton distribution
functions (PDFs). We extract a set of iron PDFs which are used to compute
x_Bj-dependent and Q^2-dependent nuclear correction factors for iron structure
functions which are req... | 0812.3370v1 |
2008-12-26 | Normal State Spin Dynamics of Five-band Model for Iron-pnictides | Normal state spin dynamics of the recently discovered iron-pnictide
superconductors is discussed by calculating spin structure factor S(q, omega)
in an itinerant five-band model within RPA approximation. Due to the
characteristic Fermi surface structure of iron-pnictide, column like response
is found at (pi, 0) in exte... | 0812.4664v1 |
2009-05-11 | Antiferromagnetically Driven Electronic Correlation in Iron Pnictides and Cuprates | The iron pnictides and the cuprates represent two families of materials,
where strong antiferromagnetic correlation drives three other distinct ordering
tendencies: (1) superconducting pairing, (2) Fermi surface distortion, and (3)
orbital current order. We propose that (1)-(3) and the antiferromagnetic
correlation are... | 0905.1711v2 |
2009-06-30 | New extended atomic data in cool star model atmospheres - Using Kurucz's new iron data in MAFAGS-OS models | Context. Cool star model atmospheres are a common tool for the investigation
of stellar masses, ages and elemental abundance composition. Theoretical
atmospheric models strongly depend on the atomic data used when calculating
them. Aims. We present the changes in flux and temperature stratification when
changing from i... | 0906.5449v1 |
2009-07-04 | Angle-Resolved Photoemission Spectroscopy of Iron-Chalcogenide Superconductor Fe1.03Te0.7Se0.3 : Strong-Coupling Superconductivity and Universality of Inter-Band Scattering | We have performed high-resolution angle-resolved photoemission spectroscopy
of iron-chalcogenide superconductor Fe1.03Te0.7Se0.3 (Tc = 13 K) to investigate
the electronic structure relevant to superconductivity. We observed a hole- and
an electron-like Fermi surfaces at the Brillouin zone center and corner,
respectivel... | 0907.0763v1 |
2009-08-19 | Sr$_2$VO$_3$FeAs: A Nanolayered Bimetallic Iron Pnictide Superconductor | One of the unifying concepts in the iron-pnictide superconductors, both for
the mechanism of magnetic ordering and of unconventional order parameter
character, has been the electron and hole Fermi surfaces that are approximately
nested. Using the density functional methods that have predicted Fermi surfaces
correctly i... | 0908.2698v3 |
2009-09-02 | Electronic correlations in the iron pnictides | In correlated metals derived from Mott insulators, the motion of an electron
is impeded by Coulomb repulsion due to other electrons. This phenomenon causes
a substantial reduction in the electron's kinetic energy leading to remarkable
experimental manifestations in optical spectroscopy. The high-Tc
superconducting cupr... | 0909.0312v1 |
2009-10-05 | Universal magnetic and structural behaviors in the iron arsenides | Commonalities among the order parameters of the ubiquitous antiferromagnetism
present in the parent compounds of the iron arsenide high temperature
superconductors are explored. Additionally, comparison is made between the well
established two-dimensional Heisenberg-Ising magnet, K$_2$NiF$_4$ and iron
arsenide systems ... | 0910.0489v1 |
2009-10-12 | Orbital selective local moment formation in iron: first principle route to an effective model | We revisit a problem of theoretical description of alpha-iron. By performing
LDA+DMFT calculations in the paramagnetic phase we find that Coulomb
interaction and, in particular Hund exchange, yields the formation of local
moments in e_g electron band, which can be traced from imaginary time
dependence of the spin-spin ... | 0910.2161v1 |
2009-12-01 | A common magnetic origin for the Invar effects in fcc iron-based ferromagnets | Using first-principles calculations, in conjunction with Ising magnetism, we
undertake a theoretical study to elucidate the origin of the experimentally
observed Invar effects in disordered fcc iron-based ferromagnets. First, we
show that our theory can account for the Invar effects in iron-nickel alloys,
the anomalies... | 0912.0215v4 |
2009-12-29 | London penetration depth and strong pair-breaking in iron-based superconductors | The low temperature variation of the London penetration depth for a number of
iron-pnictide and iron-chalcogenide superconductors is nearly quadratic,
$\Delta \lambda(T) = \beta T^n$ with $n\approx 2$. The coefficient in this
dependence shows a robust scaling, $\beta \propto 1/T_c^3$ across different
families of these ... | 0912.5346v1 |
2010-01-08 | Effect of time and storing conditions on iron forms in ferrous gluconate and Ascofer | Antianemic medicament Ascofer and ferrous gluconate, its basic iron bearing
ingredient, were studied with the use of Mossbauer spectroscopy. Room
temperature spectra gave a clear evidence that two phases of iron were present
viz. ferrous (Fe2+) as a major one with a contribution of 85+-5%, and ferric
(Fe3+) whose contr... | 1001.1218v1 |
2010-02-08 | Evidence for a full energy gap for nickel-pnictide LaNiAsO_{1-x}F_x superconductors by ^{75}As nuclear quadrupole resonance | We report systematic ^{75}As-NQR and ^{139}La-NMR studies on nickel-pnictide
superconductors LaNiAsO_{1-x}F_x (x=0, 0.06, 0.10 and 0.12). The spin lattice
relaxation rate 1/T_1 decreases below T_c with a well-defined coherence peak
and follows an exponential decay at low temperatures. This result indicates
that the sup... | 1002.1506v1 |
2010-02-09 | Iron line emission from X-ray pulsars: physical conditions and geometry of the system | We present here the preliminary results of the study of the fluorescent iron
line emission from X-ray pulsars with Be companions. We propose to use
properties of this emission to investigate the spatial distribution and
physical conditions of the matter around the compact object as well as in the
binary system as a who... | 1002.1898v1 |
2010-02-12 | Low magnetization and anisotropy in the antiferromagnetic state of undoped iron pnictides | We examine the magnetic phase diagram of iron pnictides using a five band
model. For the intermediate values of the interaction expected to hold in the
iron pnictides, we find a metallic low moment state characterized by
antiparallel orbital magnetic moments. The anisotropy of the interorbital
hopping amplitudes is the... | 1002.2584v2 |
2010-04-06 | Anion height dependence of Tc and density of states in iron based superconductors | Systematic ab initio LDA calculations were performed for all the typical
representatives of recently discovered class of iron based high-temperature
superconductors: REOFe(As,P) (RE=La,Ce,Nd,Sm,Tb), Ba2Fe2As, (Sr,Ca)FFeAs,
Sr4Sc2O6Fe2P2, LiFeAs and Fe(Se,Te). Non-monotonic behavior of total density of
states at the Fer... | 1004.0801v1 |
2010-06-11 | New Iron Arsenide Oxides (Fe2As2)(Sr4(Sc,Ti)3O8), (Fe2As2)(Ba4Sc3O7.5), and (Fe2As2)(Ba3Sc2O5) | We synthesized new layered iron arsenide oxides
(Fe2As2)(Sr4(Sc,Ti)3O8),(Fe2As2)(Ba4Sc3O7.5), and (Fe2As2)(Ba3Sc2O5). The
crystal structures of these compounds are tetragonal with a space group of
I4/mmm. The structure of (Fe2As2)(Sr4(Sc,Ti)3O8) and (Fe2As2)(Ba4Sc3O7.5)
consists of the alternate stacking of antifluorit... | 1006.2353v1 |
2010-07-13 | Phase transitions and iron-ordered moment form factor in LaFeAsO | Elastic neutron scattering studies of an optimized LaFeAsO single crystal
reveal that upon cooling, an onset of the tetragonal (T)-to-orthorhombic (O)
structural transition occurs at $T_\texttt{S} \approx 156$ K, and it exhibits a
sharp transition at $T_\texttt{P} \approx 148$ K. We argue that in the
temperature range ... | 1007.2197v1 |
2010-08-10 | Development of Powder-in-Tube Processed Iron Pnictide Wires and Tapes | The development of the PIT fabrication process of iron pnictide
superconducting wires and tapes has been carried out in order to enhance their
transport properties. Silver was found to be the best sheath material, since no
reaction layer was observed between the silver sheath and the superconducting
core. The grain con... | 1008.1735v2 |
2010-08-10 | Orbital Fluctuation Theory in Iron Pnictides: Effects of As-Fe-As Bond Angle, Isotope Substitution, and $Z^2$-Orbital Pocket on the Superconductivity | We study the pairing mechanism in iron pnictide superconductors based on the
five-orbital Hubbard-Holstein model. Due to Fe-ion oscillations, the s-wave
superconducting (SC) state without sign reversal (s_{++}-wave state) is induced
by orbital fluctuations by using realistic model parameters. The virtue of the
present ... | 1008.1765v3 |
2010-09-20 | Iron Depletion into Dust Grains in Galactic Planetary Nebulae | We present preliminary results of an analysis of the iron depletion factor
into dust grains for a sample of 20 planetary nebulae (PNe) from the Galactic
bulge. We compare these results with the ones we obtained in a prior analysis
of 28 Galactic disk PNe and 8 Galactic H II regions. We derive high depletion
factors in ... | 1009.3945v1 |
2010-10-25 | The melting curve of iron at extreme pressures: implications for planetary cores | Exoplanets with masses similar to that of Earth have recently been discovered
in extrasolar systems. A first order question for understanding their dynamics
is to know whether they possess Earth like liquid metallic cores. However, the
iron melting curve is unknown at conditions corresponding to planets of several
time... | 1010.5133v1 |
2010-11-01 | Quantitative magnetic force microscopy on permalloy dots using an iron filled carbon nanotube probe | We have characterized a new Magnetic Force Microscopy (MFM) probe based on an
iron filled carbon nanotube (FeCNT) using MFM imaging on permalloy (Py) disks
saturated in a high magnetic field perpendicular to the disk plane. The
experimental data are accurately modeled by describing the FeCNT probe as
having a single ma... | 1011.0389v1 |
2010-11-29 | Antiferromagnetic order in multi-band Hubbard models for iron-pnictides | We investigate multi-band Hubbard models for the three iron 3$d$-$t_{2g}$
bands and the two iron 3$d$-$e_g$ bands in ${\rm La O Fe As}$ by means of the
Gutzwiller variational theory. Our analysis of the paramagnetic ground state
shows that neither Hartree--Fock mean-field theories nor effective spin models
describe the... | 1011.6219v1 |
2010-12-13 | Rigidity dependence of cosmic ray escape length in the Galaxy obtained from a comparison of proton and iron spectra in the range 3-3000 GV | The simple leaky-box model of propagation of cosmic rays in the Galaxy is
quite suitable for handling data on cosmic ray nuclei energy spectra and
composition at E ? 1 GeV [1,2]. In the leakybox model a full information about
cosmic ray propagation in Galaxy is compressed to the single parameter - escape
length, Xe, ch... | 1012.2722v1 |
2010-12-30 | Pressure-Driven Quantum Criticality in An Iron-Selenide Superconductor | The discovery of superconductivity of about 30 K in iron selenides with very
large magnetic moments simulates the examination of completing orders. Here we
report a finding of pressure- induced suppression of the superconducting
transition temperature Tc and enhancement of the temperature of the resistance
hump TH thro... | 1101.0092v3 |
2011-01-05 | Dust production and mass loss in the Galactic globular cluster 47 Tucanae | Dust production among post-main-sequence stars is investigated in the
Galactic globular cluster 47 Tucanae (NGC 104) based on infrared photometry and
spectroscopy. We identify metallic iron grains as the probable dominant opacity
source in these winds. Typical evolutionary timescales of AGB stars suggest the
mass-loss ... | 1101.1096v1 |
2011-01-20 | Spin-state crossover and hyperfine interactions of ferric iron in MgSiO$_3$ perovskite | Using density functional theory plus Hubbard $U$ calculations, we show that
the ground state of (Mg,Fe)(Si,Fe)O$_3$ perovskite, a major mineral phase in
the Earth's lower mantle, has high-spin ferric iron ($S=5/2$) at both the
dodecahedral (A) and octahedral (B) site. As the pressure increases, the B-site
iron undergoe... | 1101.3819v2 |
2011-03-09 | Interstitial iron tuning of the spin fluctuations in Fe1+xTe | Using neutron inelastic scattering, we investigate the low-energy spin
fluctuations in Fe1+xTe as a function of both temperature and interstitial iron
concentration. For Fe1.057(7)Te the magnetic structure is defined by a
commensurate wavevector of (1/2,0,1/2). The spin fluctuations are gapped with a
sharp onset at 7 m... | 1103.1811v2 |
2011-03-18 | First-principles Studies for the Hydrogen Doping Effects on Iron-based Superconductors | We study hydrogen doping effects in an iron-based superconductor
LaFeAsO_(1-y) by using the first-principles calculation and explore the reason
why the superconducting transition temperature is remarkably enhanced by the
hydrogen doping. The present calculations reveal that a hydrogen cation stably
locating close to an... | 1103.3560v1 |
2011-04-18 | Optimized Orthogonal Basis Tight Binding. Application to Iron | The formal link between the linear combination of atomic orbitals approach to
density functional theory and two-center Slater-Koster tight-binding models is
used to derive an orthogonal $d$-band tight-binding model for iron with only
two fitting parameters. The resulting tight-binding model correctly predicts
the energ... | 1104.3598v1 |
2011-05-26 | Iron abundance in the prototype PG1159 star, GW Vir pulsator PG1159-035, and related objects | We performed an iron abundance determination of the hot, hydrogen deficient
post-AGB star PG1159-035, which is the prototype of the PG1159 spectral class
and the GW Vir pulsators, and of two related objects (PG1520+525, PG1144+005),
based on the first detection of Fe VIII lines in stellar photospheres. In
another PG115... | 1105.5276v1 |
2011-06-02 | Ab-initio molecular dynamics simulation of hydrogen diffusion in $α$-iron | First-principles atomistic molecular dynamics simulation in the
micro-canonical and canonical ensembles has been used to study the diffusion of
interstitial hydrogen in $\alpha$-iron. Hydrogen to Iron ratios between
$\theta=1/16 and 1/2 have been considered by locating interstitial hydrogen
atoms at random positions in... | 1106.0464v1 |
2011-07-11 | Impairment of double exchange mechanism in electron transport of iron pnictides | Double exchange mechanism is believed to favor transport along ferromagnetic
directions, the failure of which in explaining the unusual resistivity
anisotropy in iron pnictides is investigated. Several factors intrinsic to the
microscopic mechanism of transport in iron pnictides are identified and
analyzed, including t... | 1107.1952v1 |
2011-07-12 | Revealing the dual nature of magnetism in iron pnictides and iron chalcogenides using x-ray emission spectroscopy | We report Fe K beta x-ray emission spectroscopy study of local magnetic
moments in various iron based superconductors in their paramagnetic phases.
Local magnetic moments are found in all samples studied: PrFeAsO,
Ba(Fe,Co)2As2, LiFeAs, Fe1+x(Te,Se), and A2Fe4Se5 (A=K, Rb, and Cs). The moment
size varies significantly ... | 1107.2211v1 |
2011-08-13 | Imaging the coexistence of superconductivity and a charge density modulation in K0.73Fe1.67Se2 superconductor | We report scanning tunneling microscopy studies of the local structural and
electronic properties of the iron selenide superconductor K0.73Fe1.67Se2 with
TC = 32K. On the atomically resolved FeSe surface, we observe well-defined
superconducting gap and the microscopic coexistence of a charge density
modulation with roo... | 1108.2798v1 |
2011-10-03 | Block Antiferromagnetism and Checkerboard Charge Ordering in Alkali-doped Iron Selenides $R$$_{1-x}$Fe$_{2-y}$Se$_2$ | By performing first-principles electronic structure calculations and
analyzing effective magnetic model of alkali-doped iron selenides, we show that
the materials without iron vacancies should approach a novel checkerboard phase
in which each four Fe sites group together in tetragonal structure. The
checkerboard phase ... | 1110.0372v1 |
2011-11-25 | Growth and electronic and magnetic structure of iron oxide films on Pt(111) | Ultrathin (111)-oriented polar iron oxide films were grown on a Pt(111)
single crystal either by the reactive deposition of iron or oxidation of
metallic iron monolayers. These films were characterized using low energy
electron diffraction, scanning tunneling microscopy and conversion electron
Mossbauer spectroscopy. T... | 1111.5938v2 |
2011-12-07 | Relativistic iron K X-ray Reverberation in NGC 4151 | Recent X-ray observations have enabled the study of reverberation delays in
AGN for the first time. All the detections so far are in sources with a strong
soft excess, and the measured delay is between the hard (1-3 keV) direct
continuum and the soft excess (0.5-1 keV), interpreted as the reflection
continuum smeared b... | 1112.1717v2 |
2012-02-06 | Unconventional superconducting gap via spin fluctuations in iron-vacancy ordered A$_{y}$Fe$_{2-x}$Se$_{2}$ | Based on an effective 12-orbital tight-binding model, we examine the
superconducting states induced by the antiferromagnetic fluctuations for
iron-vacancy-ordered A$_{y}$Fe$_{2-x}$Se$_{2}$. It is shown that due to the
broken reflection symmetry induced by the iron vacancies, new superconducting
states with $C_{4h}$ sym... | 1202.1063v2 |
2012-02-17 | Electronic and Magnetic Structures of Chain Structured Iron Selenide Compounds | Electronic and magnetic structures of iron selenide compounds Ce2O2FeSe2
(2212\ast) and BaFe2Se3(123\ast) are studied by the first-principles
calculations. We find that while all these compounds are composed of
one-dimensional (1D) Fe chain (or ladder) structures, their electronic
structures are not close to be quasi-1... | 1202.4016v1 |
2012-03-11 | Iron-Based Superconductors: $S_4$ Symmetry Superconductors | I elaborate the construction of the recent two-orbital model for iron-based
superconductors\cite{hu-hao} and discuss the properties of superconducting(SC)
phases based on the $S_4$ symmetry. I demonstrate further that the underlining
electronic structure is an almost decoupled two-orbital model obeying the $S_4$
symmet... | 1203.2304v3 |
2012-06-27 | Quantum Monte Carlo Study of Pairing Symmetry and Correlation in Iron-based Superconductors | We perform a systematic quantum Monte Carlo study of the pairing correlation
in the $S_4$ symmetric microscopic model for iron-based superconductors. It is
found that the pairing with an extensive s-wave symmetry robustly dominates
over other pairings at low temperature in reasonable parameter region. The
pairing susce... | 1206.6277v2 |
2012-07-23 | A general moment NRIXS approach to the determination of equilibrium Fe isotopic fractionation factors: application to goethite and jarosite | We measured the reduced partition function ratios for iron isotopes in
goethite FeO(OH), potassium-jarosite KFe3(SO4)2(OH)6, and hydronium-jarosite
(H3O)Fe3(SO4)2(OH)6, by Nuclear Resonant Inelastic X-Ray Scattering (NRIXS,
also known as Nuclear Resonance Vibrational Spectroscopy -NRVS- or Nuclear
Inelastic Scattering ... | 1207.5559v1 |
2012-08-28 | Orbital-selective Mott Phase in Multiorbital Models for Alkaline Iron Selenides K(1-x)Fe(2-y)Se2 | We study a multiorbital model for the alkaline iron selenides
K(1-x)Fe(2-y)Se2 using a slave-spin method. With or without ordered vacancies,
we identify a metal-to-Mott-insulator transition at the commensurate filling of
six 3d electrons per iron ion. For Hund's couplings beyond a threshold value,
this occurs via an in... | 1208.5547v1 |
2012-08-30 | A Short Review of the $S_4$ Symmetric Microscopic Model for Iron-Based High Temperature Superconductors | We briefly review the recently constructed two orbital microscopic model for
iron-based superconductors based on $S_4$ symmetry (PRX 2 021009(2012)). With
this faithful representation of the kinematics of the tri-layer FeAs or FeSe
structure, the model provides answers and physical pictures to fundamental
questions rel... | 1208.6201v1 |
2012-12-17 | The first-principles study of thermodynamical properties of random magnetic overlayers on fcc-Cu(001) substrate | We present the theoretical study of thermodynamical properties of fcc-Cu(001)
substrate covered by iron-cobalt monolayer as well as by incomplete iron layer.
The effective two-dimensional Heisenberg Hamiltonian is constructed from first
principles and properties of exchange interactions are investigated. The Curie
temp... | 1212.4057v1 |
2013-02-22 | Nematicity driven by hybridization in iron-based superconductors | In this paper we study an effective model for the normal state of iron-based
superconductors. It has separate, but interacting itinerant and localized
degrees of freedom, originating from the d_xz and d_yz, and from d_xy iron
orbitals respectively. At low temperatures, below a mean-field phase
transition, these differe... | 1302.5739v2 |
2013-03-04 | Broad K$α$ iron line from accretion disks around traversable wormholes | It has been proposed that the supermassive black hole candidates at the
centers of galaxies might be wormholes formed in the early Universe and
connecting our Universe with other sister Universes. The analysis of the
profile of the relativistic K$\alpha$ iron line is currently the only available
approach to probe the s... | 1303.0624v2 |
2013-03-11 | Mechanism for Odd Parity Superconductivity in Iron-Based Superconductors | Under the assumption that superconducting pairing is driven by local d-p
hybridization, we show that the superconducting state in iron-based
superconductors is classified as an odd parity s-wave spin-singlet pairing
state in a single trilayer FeAs/Se, the building block of the materials. In a
low energy effective model... | 1303.2624v2 |
2013-03-25 | Upturn observed in heavy nuclei to iron ratios by the ATIC-2 experiment | The ratios of fluxes of heavy nuclei from sulfur (Z=16) to chromium (Z=24) to
the flux of iron were measured by the ATIC-2 experiment. The ratios are
decreasing functions of energy from 5 GeV/n to approximately 80 GeV/n, as
expected. However, an unexpected sharp upturn in the ratios are observed for
energies above 100 ... | 1303.6108v1 |
2013-04-08 | Spin states of iron impurities in magnesium oxide under pressure: A possible intermediate state | Ferropericlase (Mg,Fe)O is a major lower mantle mineral, and studying its
properties is a fundamental step toward understanding the Earth's interior.
Here, we performed a first-principles investigation on the properties of iron
as an isolated impurity in magnesium oxide, which is the condition of
ferropericlase under w... | 1304.2227v1 |
2013-05-15 | Iron impurities in gold and silver: Comparison of transport measurements to numerical renormalization group calculations exploiting non-Abelian symmetries | We consider iron impurities in the noble metals gold and silver and compare
experimental data for the resistivity and decoherence rate to numerical
renormalization group results. By exploiting non-Abelian symmetries we show
improved numerical data for both quantities as compared to previous
calculations [Costi et al., ... | 1305.3551v2 |
2013-07-08 | K$α$ iron line profile from accretion disks around regular and singular exotic compact objects | The nature of the super-massive black hole candidates in galactic nuclei can
be tested by analyzing the profile of the K$\alpha$ iron line observed in their
X-ray spectrum. In this paper, we consider the possibility that the spacetime
in the immediate vicinity of these objects may be described by some non vacuum
exact ... | 1307.2106v2 |
2013-07-18 | Iron Line Variability of Discoseismic Corrugation Modes | Using a fast semi-analytic raytracing code, we study the variability of
relativistically broadened iron lines due to discoseismic oscillations
concentrated in the inner-most regions of accretion discs around black holes.
The corrugation mode, or c-mode, is of particular interest as its natural
frequency corresponds wel... | 1307.4971v1 |
2013-07-31 | Determination of the iron content of Cepheids from the shape of their light curves | We present the study of the metallicity dependence of the Fourier amplitude
ratios R_21 and R_31 for the light curves of short-period Galactic classical
Cepheids in B, V, R_C and I_C bands. Based on the available photometric and
spectroscopic data we determined the relations between the atmospheric iron
abundance, [Fe/... | 1307.8275v1 |
2013-08-19 | Broad iron lines in neutrons stars: dynamical broadening or wind scattering? | Broad iron emission lines are observed in many accreting systems from black
holes in AGN and X-ray binaries to neutron star low-mass X-ray binaries. The
origin of the line broadening is often interpreted as due to dynamical
broadening and relativistic effects. However, alternative interpretations have
been proposed, in... | 1308.4023v1 |
2013-09-17 | A Chandra view of the clumpy reflector at the heart of the Circinus galaxy | We present a spectral and imaging analysis of the X-ray reflecting structure
at the heart of the Circinus galaxy, investigating the innermost regions
surrounding the central black hole. By studying an archival 200 ks Chandra
ACIS-S observation, we are able to image the extended clumpy structure
responsible for both col... | 1309.4456v1 |
2013-10-15 | Atomic structure of grain boundaries in iron modeled using the atomic density function | A model based on the continuous atomic density function (ADF) approach is
applied to predict the atomic structure of grain boundaries (GBs) in iron.
Symmetrical [100] and [110] tilt GBs in bcc iron are modeled with the ADF
method and relaxed afterwards in molecular dynamics (MD) simulations. The shape
of the GB energy ... | 1310.3964v2 |
2013-12-17 | Ground state pairing correlations in the $S_4$ symmetric microscopic model for iron-based superconductors | We present the ground state pairing correlations in the $S_4$ symmetric
microscopic model for iron-based superconductors, computed with the
constrained-path Monte Carlo method. For various electron fillings and
interaction strengths, we find that the $s_{xy}$ pairing dominates over other
pairing correlations and is pos... | 1312.4777v2 |
2014-03-05 | Electrical and optical properties of fluid iron from compressed to expanded regime | Using quantum molecular dynamics simulations, we show that the electrical and
optical properties of fluid iron change drastically from compressed to expanded
regime. The simulation results reproduce the main trends of the electrical
resistivity along isochores and are found to be in good agreement with
experimental dat... | 1403.1030v1 |
2014-06-07 | Optical conductivity of iron-based superconductors | The new family of unconventional iron-based superconductors discovered in
2006 immediately relieved their copper-based high-temperature predecessors as
the most actively studied superconducting compounds in the world. The
experimental and theoretical effort made in order to unravel the mechanism of
superconductivity in... | 1406.1879v1 |
2014-06-09 | Manipulation of gap nodes by uniaxial strain in iron-based superconductors | In the iron pnictides and chalcogenides, multiple orbitals participate in the
superconducting state, enabling different gap structures to be realized in
distinct materials. Here we argue that the spectral weights of these orbitals
can in principle be controlled by a tetragonal symmetry-breaking uniaxial
strain, due to ... | 1406.2388v2 |
2014-07-24 | Parallax diagnostics of radiation source geometric dilution for iron opacity experiments | Experimental tests are in progress to evaluate the accuracy of the modeled
iron opacity at solar interior conditions [J.E. Bailey et al., Phys. Plasmas
16, 058101 (2009)]. The iron sample is placed on top of the Sandia National
Laboratories z-pinch dynamic hohlraum (ZPDH) radiation source. The samples are
heated to 150... | 1407.6645v1 |
2014-09-23 | Superconductivity and its mechanism in an ab initio model for electron-doped LaFeAsO | Two families of high temperature superconductors whose critical temperatures
are higher than 50K are known. One is the copper oxides and the other is the
iron-based superconductors. Comparisons of mechanisms between these two in
terms of common ground as well as distinctions will greatly help in searching
for higher Tc... | 1409.6536v1 |
2014-10-14 | Entangled Orbital Triplet Pairs in Iron-Based Superconductors | A key question in high temperature iron-based superconductivity is the
mechanism by which the paired electrons minimize their strong mutual Coulomb
repulsion. While electronically paired superconductors generally avoid the
Coulomb interaction through the formation of nodal, higher angular momentum
pairs, iron based sup... | 1410.3554v1 |
2014-10-27 | First-principles study of intermediate-spin ferrous iron in the Earth's lower mantle | Spin crossover of iron is of central importance in solid Earth geophysics. It
impacts all physical properties of minerals that altogether constitute $\sim
95$ vol\% of the Earth's lower mantle: ferropericlase [(Mg,Fe)O] and Fe-bearing
magnesium silicate (MgSiO$_3$) perovskite. Despite great strides made in the
past dec... | 1410.7200v1 |
2014-12-04 | Magnetism of the Fe$^{2+}$ and Ce$^{3+}$ sublattices in Ce$_{2}$O$_{2}$FeSe$_{2}$: a combined neutron powder diffraction, inelastic neutron scattering and density functional study | The discovery of superconductivity in the 122 iron selenide materials above
30 K necessitates an understanding of the underlying magnetic interactions. We
present a combined experimental and theoretical investigation of magnetic and
semiconducting Ce$_{2}$O$_{2}$FeSe$_{2}$ composed of chains of edge-linked iron
selenid... | 1412.1773v1 |
2014-12-23 | Atomic, electronic and magnetic structure of graphene/iron and nickel interfaces: theory and experiment | First-principles calculations of the effect of carbon coverage on the atomic,
electronic and magnetic structure of nickel and iron substrates demonstrate
insignificant changes in the interatomic distances and magnetic moments on the
atoms of the metallic substrates. The coverage of the iron surface by mono- and
few-lay... | 1412.7291v1 |
2015-03-20 | Thermoelasticity of Fe2+-bearing bridgmanite | We present LDA+U calculations of high temperature elastic properties of
bridgmanite with composition (Mg$_{(1-x)}$Fe$_{x}^{2+}$)SiO$_3$ for
$0\le{x}\le0.125$. Results of elastic moduli and acoustic velocities for the
Mg-end member (x=0) agree very well with the latest high pressure and high
temperature experimental mea... | 1503.05983v1 |
2015-05-07 | Type Ia Supernova Remnants: Shaping by Iron Bullets | Using 2D numerical hydrodynamical simulations of type Ia supernova remnants
(SNR Ia) we show that iron clumps few times denser than the rest of the SN
ejecta might form protrusions in an otherwise spherical SNR. Such protrusions
exist in some SNR Ia, e.g., SNR 1885 and Tycho. Iron clumps are expected to
form in the def... | 1505.02034v2 |
2015-07-13 | Electronic and magnetic properties of orthorhombic iron selenide (FeSe) | Iron orbitals in orthorhombic iron selenide (FeSe) can produce charge-like
multipoles that are polar (parity-odd). Orbitals in question include Fe(3d),
Fe(4p) and p-type ligands that participate in transport properties and bonding.
The polar multipoles may contribute weak, space-group forbidden Bragg spots to
diffracti... | 1507.03449v3 |
2015-07-16 | Feasibility of pulsed inflector for g-2ring (1) | We revise a possibility of usage iron-free fast pulsed magnet as inflector
for g-2 ring, coming to conclusion that it is a feasible option. | 1507.04796v1 |
2015-08-06 | Charge Nematicity and Electronic Raman Scattering in Iron-based Superconductors | We review the recent developments in electronic Raman scattering measurements
of charge nematic fluctuations in iron-based superconductors. A simple
theoretical framework of a $d$-wave Pomeranchuk transition is proposed in order
to capture the salient features of the spectra. We discuss the available Raman
data in the ... | 1508.01319v2 |
2015-08-29 | Competing Magnetic Fluctuations in Iron Pnictide Superconductors: Role of Ferromagnetic Spin Correlations Revealed by NMR | In the iron pnictide superconductors, theoretical calculations have
consistently shown enhancements of the static magnetic susceptibility at both
the stripe-type antiferromagnetic (AFM) and in-plane ferromagnetic (FM)
wavevectors. However, the possible existence of FM fluctuations has not yet
been examined from a micro... | 1508.07506v1 |
2015-12-23 | Giant biquadratic interaction induced magnetic anisotropy in the iron-based superconductor AxFe2-ySe2 | The emergence of the electron-pocket only iron-based superconductor
AxFe2-ySe2 (A = alkali metal) challenges the Fermi-surface nesting picture
established in iron-pnictides. It was widely believed that magnetism is
correlated with the superconductivity in AxFe2-ySe2. Unfortunately, the highly
anisotropic exchange param... | 1512.07327v1 |
2016-01-08 | Isotropic Cooper Pairs with Emergent Sign Changes in Single-Layer Iron Superconductor | We model a single layer of heavily electron-doped FeSe by spin-1/2 moments
over a square lattice of iron atoms that include the 3d xz and 3d yz orbitals,
at strong on-site Coulomb repulsion. Above half filling, we find emergent hole
bands below the Fermi level at the center of the one-iron Brillouin zone in a
half meta... | 1601.01860v3 |
2016-03-18 | Stability mechanisms of high current transport in iron-chalcogenides superconducting films | The improvement in the fabrication techniques of iron-based superconductors
have made these materials real competitors of high temperature superconductors
and MgB$_2$. In particular, iron-chalcogenides have proved to be the most
promising for the realization of high current carrying tapes. But their use on
a large scal... | 1603.05980v1 |
2016-05-15 | Nonlocal correlations in the vicinity of the $α$-$γ$ phase transition in iron within a DMFT plus spin-fermion model approach | We consider nonlocal correlations in iron in the vicinity of the
$\alpha$-$\gamma$ phase transition within the spin-rotationally-invariant
dynamical mean-field theory (DMFT) approach, combined with the recently
proposed spin-fermion model of iron. The obtained nonlocal corrections to DMFT
yield a decrease of the Curie ... | 1605.04589v2 |
2016-06-01 | Quasi-particle bands and structural phase transition of iron from Gutzwiller Density-Functional Theory | We use the Gutzwiller Density Functional Theory to calculate ground-state
properties and bandstructures of iron in its body-centered-cubic (bcc) and
hexagonal-close-packed (hcp) phases. For a Hubbard interaction $U=9\, {\rm eV}$
and Hund's-rule coupling $J=0.54\, {\rm eV}$ we reproduce the lattice
parameter, magnetic m... | 1606.00307v1 |
2016-08-03 | Moiré-free ultrathin iron oxide film: FeO(111) on Ag(111) | Ultrathin iron oxide films epitaxially grown on the (111)- and
(0001)-oriented metal single crystal supports exhibit unique electronic,
catalytic and magnetic properties not observed for the corresponding bulk
oxides. These properties originate mainly from the presence of Moir\'e
superstructures which, in turn, disqual... | 1608.01376v2 |
2016-08-21 | Coexistence of antiferromagnetic and ferromagnetic spin correlations in Ca(Fe1-xCox)2As2 revealed by 75As nuclear magnetic resonance | Recent nuclear magnetic resonance (NMR) measurements revealed the coexistence
of stripe-type antiferromagnetic (AFM) and ferromagnetic (FM) spin correlations
in both the hole- and electron-doped BaFe$_2$As$_2$ families of iron-pnictide
superconductors by a Korringa ratio analysis. Motivated by the NMR work, we
investig... | 1608.05952v1 |
2016-08-29 | Frustrated magnetism and bicollinear antiferromagnetic order in FeTe | Iron chalcogenides display a rich variety of electronic orders in their phase
diagram. A particularly enigmatic case is FeTe, a metal which possesses
co-existing hole and electron Fermi surfaces as in the iron pnictides but has a
distinct ($\pi$/2,$\pi/2$) bicollinear antiferromagnetic order in the Fe square
lattice. W... | 1608.08206v1 |
2016-09-12 | Spin excitations in hole-overdoped iron-based superconductors | Understanding the overall features of magnetic excitation is essential for
clarifying the mechanism of Cooper pair formation in iron-based
superconductors. In particular, clarifying the relationship between magnetism
and superconductivity is a central challenge because magnetism may play a key
role in their exotic supe... | 1609.03335v1 |
2016-09-21 | Nematicity at the Hund's metal crossover in iron superconductors | The theoretical understanding of the nematic state of iron-based
superconductors and especially of FeSe is still a puzzling problem. Although a
number of experiments calls for a prominent role of local correlations and
place iron superconductors at the entrance of a Hund metal state, the effect of
the electronic correl... | 1609.06672v2 |
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