publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2009-03-24 | Timescale Resolved Spectroscopy of Cyg X-1 | We propose the timescale-resolved spectroscopy (TRS) as a new method to
combine the timing and spectral study. TRS is based on the time domain power
spectrum and reflects the variable amplitudes of spectral components on
different timescales. We produce the TRS with the RXTE PCA data for Cyg X-1 and
studied the spectra... | 0903.4118v1 |
2009-03-25 | Three- to Two-Dimensional Transition of the Electronic Structure in CaFe2As2 - parent compound for an iron arsenic high temperature superconductor | We use angle-resolved photoemission spectroscopy (ARPES) to study the
electronic properties of CaFe2As2 - parent compound of a pnictide
superconductor. We find that the structural and magnetic transition is
accompanied by a three- to two-dimensional (3D-2D) crossover in the electronic
structure. Above the transition te... | 0903.4388v1 |
2009-03-26 | Superconductivity induced by ruthenium substitution in an iron arsenide: investigation of SrFe2-xRuxAs2 (0 <= x <= 2) | The magnetism in SrFe2As2 can be suppressed by electron doping through a
small substitution of Fe by Co or Ni, giving way to superconductivity. We
demonstrate that a massive substitution of Fe by isovalent ruthenium similarly
suppresses the magnetic ordering in SrFe2-xRuxAs2 and leads to bulk
superconductivity for 0.6 ... | 0903.4668v2 |
2009-03-27 | The electronic structure of LiFeAs and NaFeAs probed by resonant inelastic x-ray scattering spectra | Results of resonant inelastic X-ray scattering (RIXS) measurements at Fe
L-edges and electronic structure calculations of LiFeAs and NaFeAs are
presented. Both experiment and theory show that in the vicinity of the Fermi
energy, the density of states is dominated by contributions from Fe 3d-states.
The comparison of Fe... | 0903.4901v2 |
2009-03-29 | Anisotropic spin fluctuations and multiple superconducting gaps in hole-doped Ba_0.7K_0.3Fe_2As_2: NMR in a single crystal | We report the first ^{75}As-NMR study on a single crystal of the hole-doped
iron-pnictide superconductor Ba_{0.7}K_{0.3}Fe_2As_{2} (T_c = 31.5 K). We find
that the Fe antiferromagnetic spin fluctuations are anisotropic and are weaker
compared to underdoped copper-oxides or cobalt-oxide superconductors. The spin
lattice... | 0903.5098v2 |
2009-04-06 | Redshift Evolution in the Iron Abundance of the Intracluster Medium | Clusters of galaxies provide a closed box within which one can determine the
chemical evolution of the gaseous baryons with cosmic time. We studied this
metallicity evolution in the hot X-ray emitting baryons through an analysis of
XMM-Newton observations of 29 galaxy clusters in the redshift range 0.3 < z <
1.3. Taken... | 0904.1007v1 |
2009-04-06 | Is There a Dark Matter Signal in the Galactic Positron Annihilation Radiation? | Assuming Galactic positrons do not go far before annhilating, a difference
between the observed 511 keV annihilation flux distribution and that of
positron production, expected from beta-plus decay in Galactic iron
nucleosynthesis, was evoked as evidence of a new source and a signal of dark
matter. We show, however, th... | 0904.1025v3 |
2009-04-09 | Evaluating the locality of intrinsic precession damping in transition metals | The Landau-Lifshitz-Gilbert damping parameter is typically assumed to be a
local quantity, independent of magnetic configuration. To test the validity of
this assumption we calculate the precession damping rate of small amplitude
non-uniform mode magnons in iron, cobalt, and nickel. At scattering rates
expected near an... | 0904.1455v1 |
2009-04-11 | Three-band s+- Eliashberg theory and the superconducting gaps of iron pnictides | The experimental critical temperatures and gap values of the superconducting
pnictides of both the 1111 and 122 families can be simultaneously reproduced
within the Eliashberg theory by using a three-band model where the dominant
role is played by interband interactions and the order parameter undergoes a
sigh reversal... | 0904.1808v2 |
2009-04-14 | Optimizing the flux coupling between a nanoSQUID and a magnetic particle using atomic force microscope nanolithography | We present results of Niobium based SQUID magnetometers for which the
weak-links are engineered by the local oxidation of thin films using an Atomic
Force Microscope (AFM). Firstly, we show that this technique allows the
creation of variable thickness bridges with 10 nm lateral resolution. Precise
control of the weak-l... | 0904.2100v1 |
2009-04-14 | The Electronic Phase Diagram of the Iron-based High Tc Superconductor Ba(Fe(1-x)Co(x))2As2 Under Hydrostatic Pressure (0 < x <0.099) | We report comprehensive resistivity measurements of single crystalline
samples of the Ba(Fe(1-x)Co(x))2As2 high Tc superconductor under hydrostatic
pressure up to 2.75 GPa and over a broad concentration range, 0 < x < 0.099. We
show that application of pressure progressively suppresses the SDW transition
temperature, T... | 0904.2215v1 |
2009-04-17 | Relativistically broadened iron line in the SUZAKU observation of the neutron star X-ray binary 4U 1705-44 | The X-ray spectra of accreting compact objects often exhibit discrete
emission features associated with fluorescent emission in the accretion disk,
the strongest of which is the Fe Kalpha fluorescence line at 6.4--6.97keV.
These reflection features are amongst the best tools in the study of the inner
region of accretio... | 0904.2747v1 |
2009-04-19 | First-principles study of the effect of Fe impurities in MgO at geophysically relevant pressures | The self-interaction corrected local spin density (SIC-LSD) formalism and the
standard GGA treatment of the exchange-correlation energy have been applied to
study the collapse of the magnetic moment of Fe impurities in MgO. The system
Mg_{1-x}Fe_xO is believed to be the second most abundant mineral in the Earth's
lower... | 0904.2901v1 |
2009-04-24 | Effect of electron-doping on spin excitations of underdoped BaFe$_{1.96}$Ni$_{0.04}$As$_{2}$ | We use neutron scattering to study magnetic order and spin excitations in
BaFe$_{1.96}$Ni$_{0.04}$As$_{2}$. On cooling, the system first changes the
lattice symmetry from tetragonal to orthoromhbic near $\sim$97 K, and then
orders antiferromagnetically at $T_N=91$ K before developing weak
superconductivity below $\sim$... | 0904.3775v1 |
2009-04-24 | Microscopic origin of magnetism and magnetic interactions in ferropnictides | One year after their initial discovery, two schools of thought have
crystallized regarding the electronic structure and magnetic properties of
ferropnictide systems. One postulates that these are itinerant weakly
correlated metallic systems that become magnetic by virtue of spin-Peierls type
transition due to near-nest... | 0904.3857v1 |
2009-04-24 | Efficacy of surface error corrections to density functional theory calculations of vacancy formation energy in transition metals | We calculate properties like equilibrium lattice parameter, bulk modulus and
monovacancy formation energy for nickel (Ni), iron (Fe) and chromium (Cr) using
Kohn-Sham density functional theory (DFT). We compare relative performance of
local density approximation (LDA) and generalized gradient approximation (GGA)
for pr... | 0904.3859v2 |
2009-04-27 | The 13C Pocket in Low Mass AGB Stars | It is well known that thermally pulsing Asymptotic Giant Branch stars with
low mass play a relevant role in the chemical evolution. They have synthesized
about 30% of the galactic carbon and provide an important contribution to the
nucleosynthesis of heavy elements (A>80). The relevant nucleosynthesis site is
the He-ri... | 0904.4163v1 |
2009-04-27 | Fermi liquid state and enhanced electron correlations in the new iron pnictide CaFe$_4$As$_3$ | The newly discovered CaFe$_4$As$_3$ system displays low-temperature Fermi
liquid behavior, with enhanced electron-electron correlations. At high
temperatures, the magnetic susceptibility shows Curie-Weiss behavior, with a
large temperature-independent contribution. Antiferromagnetic ordering is
observed below T$_N$ = (... | 0904.4188v1 |
2009-04-29 | Can mass loss and overshooting prevent the excitation of g-modes in blue supergiants? | Thanks to their past history on the main sequence phase, supergiant massive
stars develop a convective shell around the helium core. This intermediate
convective zone (ICZ) plays an essential role in governing which g-modes are
excited. Indeed a strong radiative damping occurs in the high density radiative
core but the... | 0904.4641v1 |
2009-05-04 | Low Temperature Crystal Structure and 57Fe Moessbauer Spectroscopy of Sr3Sc2O5Fe2As2 | The crystal structure of the layered iron arsenide Sr3Sc2O5Fe2As2 was
determined between 300 and 10 K. The lattice parameters of the tetragonal cell
decrease anisotropically according to delta(c)/c : delta(a)/a = 4.2, which
results in a slight flattening of the As-Fe-As bond angle within the FeAs
layers. No indication ... | 0905.0337v1 |
2009-05-05 | Structural and magnetic phase transitions in Na$_{1-δ}$FeAs | We use neutron scattering to study the spin and lattice structures of single
crystal and powder samples of Na$_{1-\delta}$FeAs ($T_c = 23$ K). On cooling
from room temperature, the system goes through a series of phase transitions:
first changing the crystal symmetry from tetragonal to orthorhombic at 49 K,
then orderi... | 0905.0525v1 |
2009-05-08 | The Multiverse Hierarchy | I survey physics theories involving parallel universes, arguing that they
form a natural four-level hierarchy of multiverses allowing progressively
greater diversity. Level I: A generic prediction of inflation is an infinite
ergodic universe, which contains Hubble volumes realizing all initial
conditions -- including a... | 0905.1283v1 |
2009-05-12 | Capture and Indirect Detection of Inelastic Dark Matter | We compute the capture rate for Dark Matter in the Sun for models where the
dominant interaction with nuclei is inelastic -- the Dark Matter up-scatters to
a nearby dark "partner" state with a small splitting of order a 100 keV. Such
models have previously been shown to be compatible with DAMA/LIBRA data, as
well as da... | 0905.1847v2 |
2009-05-12 | Strong-coupling Spin-singlet Superconductivity with Multiple Full Gaps in Hole-doped Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ Probed by Fe-NMR | We present $^{57}$Fe-NMR measurements of the novel normal and
superconducting-state characteristics of the iron-arsenide superconductor
Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ ($T_c$ = 38 K). In the normal state, the
measured Knight shift and nuclear spin-lattice relaxation rate $(1/T_1)$
demonstrate the development of wave-nu... | 0905.1896v1 |
2009-05-16 | Strong electron-electron correlation and weak localization in CeO_{0.9}F_{0.1}Fe_{1-x}Co_xAs | Electron-doping of the semimetal (CeOFeAs) by either fluorine (max Tc ~ 43
K)or cobalt (max Tc ~ 11 K) leads to superconductivity. Here we show the effect
of transition metal (Co) substitution at the iron site on the superconducting
properties of CeO0.9F0.1FeAs (Tc ~38 K)to understand the interplay of charge
carriers i... | 0905.2679v1 |
2009-05-19 | The fourth Dimension | In different passages of his dialogues, Plato showed deep
mathematically-based physical insights. Regrettably most readers overlooked the
respective statements, or they utterly did not understand those hints since
they were full of philological fallacious terms. Respectable translators
misinterpreted such statements an... | 0905.3048v2 |
2009-05-19 | Testing astrophysical models for the PAMELA positron excess with cosmic ray nuclei | The excess in the positron fraction reported by the PAMELA collaboration has
been interpreted as due to annihilation or decay of dark matter in the Galaxy.
More prosaically, it has been ascribed to direct production of positrons by
nearby pulsars, or due to pion production during stochastic acceleration of
hadronic cos... | 0905.3152v3 |
2009-05-19 | Surface Geometric and Electronic Structure of BaFe2As2(001) | BaFe2As2 exhibits properties characteristic of the parent compounds of the
newly discovered iron (Fe)-based high-TC superconductors. By combining the real
space imaging of scanning tunneling microscopy/spectroscopy (STM/S) with
momentum space quantitative Low Energy Electron Diffraction (LEED) we have
identified the su... | 0905.3194v1 |
2009-05-20 | Accelerated search kinetics mediated by redox reactions of DNA repair enzymes | A Charge Transport (CT) mechanism has been proposed in several papers (e.g.,
Yavin, et al. PNAS, v102 3546 (2005)) to explain the localization of Base
Excision Repair (BER) enzymes to lesions on DNA. The CT mechanism relies on
redox reactions of iron-sulfur cofactors that modify the enzyme's binding
affinity. These red... | 0905.3211v1 |
2009-05-20 | Topological change of the Fermi surface in ternary iron-pnictides with reduced c/a ratio: A dHvA study of CaFe2P2 | We report a de Haas-van Alphen effect study of the Fermi surface of CaFe2P2
using low temperature torque magnetometry up to 45 T. This system is a close
structural analogue of the collapsed tetragonal non-magnetic phase of CaFe2As2.
We find the Fermi surface of CaFe2P2 to differ from other related ternary
phosphides in... | 0905.3305v1 |
2009-05-20 | Looking for pulsations in HgMn stars through CoRoT lightcurves | HgMn Chemically Peculiar stars are among the quietest stars of the
main-sequence. However, according to theoretical predictions, these stars could
have pulsations related to the very strong overabundances of iron peak
elements, which are produced by atomic diffusion in upper layers. Such
pulsations have never been dete... | 0905.3340v1 |
2009-05-29 | Ferromagnetic resonance linewidth in ultrathin films with perpendicular magnetic anisotropy | Transition metal ferromagnetic films with perpendicular magnetic anisotropy
(PMA) have ferromagnetic resonance (FMR) linewidths that are one order of
magnitude larger than soft magnetic materials, such as pure iron (Fe) and
permalloy (NiFe) thin films. A broadband FMR setup has been used to investigate
the origin of th... | 0905.4779v2 |
2009-05-31 | Nodeless superconducting gap in electron-doped BaFe$_{1.9}$Ni$_{0.1}$As$_2$ probed by quasiparticle heat transport | The in-plane thermal conductivity $\kappa$ of electron-doped iron-arsenide
superconductor BaFe$_{1.9}$Ni$_{0.1}$As$_2$ ($T_c$ = 20.3 K) single crystal was
measured down to 70 mK. In zero field, the absence of a residual linear term
$\kappa_0/T$ at $ T \to 0$ is strong evidence for nodeless superconducting gap.
In magne... | 0906.0138v2 |
2009-06-01 | $π$-junction to probe antiphase s-wave pairing in iron pnictide superconductors | Josephson junctions between a $FeAs$-based superconductor with antiphase
s-wave pairing and a conventional s-wave superconductor are studied. The
translational invariance in a planar junction between a single crystal pnictide
and an aluminum metal greatly enhances the relative weight of electron pockets
in the pnictide... | 0906.0169v3 |
2009-06-04 | Neutrino deuteron reaction in the heating mechanism of core-collapse supernovae | We examine a potential role of the neutrino deuteron reactions in the
mechanism of supernova explosion by evaluating the energy transfer cross
section for the neutrino heating. We calculate the energy loss rate due to the
neutrino absorptions through the charged-current process as well as the
neutrino scattering throug... | 0906.0856v1 |
2009-06-09 | Fabrication of the iron-based superconducting wire using Fe(Se, Te) | We have fabricated the Fe(Se, Te) superconducting wire by a special process
based on a powder-in-tube method. The pure Fe tube plays the role of not only
the sheath but also the raw material for synthesizing the superconducting
phases. We succeeded in observing zero resistivity current on the
current-voltage measuremen... | 0906.1636v2 |
2009-06-09 | Particle Propagation in the Galactic Center and Spatial Distribution of Non-Thermal X-rays | We showed that if the non-thermal emission from the Galactic center in the
range 14-40 keV is due to inverse bremsstrahlung emission of subrelativistic
protons, their interactions with hot and cold fractions of the interstellar
medium are equally important. Our estimation show that about 30% of the total
non-thermal fl... | 0906.1712v1 |
2009-06-10 | Superconductivity in SmFe1-xMxAsO (M = Co, Rh, Ir) | In this paper we report the comparative study of superconductivity by 3d
(Co), 4d (Rh), 5d (Ir) element doping in SmFeAsO. X-ray diffraction patterns
indicate that the material has formed the ZrCuSiAs-type structure with a space
group P4/nmm. It is found that the antiferromagnetic spin-density-wave (SDW)
order in the p... | 0906.1898v1 |
2009-06-10 | Spectroscopic Imaging Scanning Tunneling Microscopy as a Probe of Orbital Structures and Ordering | Unlike charge and spin, the orbital degree of freedom of electrons in
transition metal oxides is difficult to detect. We present the theoretical
study of a new detection method in metallic orbitally active systems by
analyzing the quasiparticle scattering interference (QPI) pattern of the
spectroscopic imaging scanning... | 0906.1973v3 |
2009-06-10 | Cosmic-ray origin in OB associations and preferential acceleration of refractory elements: Evidence from abundances of elements 26Fe through 34Se | We report abundances of elements from 26Fe to 34Se in the cosmic radiation
measured during fifty days of exposure of the Trans-Iron Galactic Element
Recorder (TIGER) balloon-borne instrument. These observations add support to
the concept that the bulk of cosmic-ray acceleration takes place in OB
associations, and they ... | 0906.2021v1 |
2009-06-19 | Homogeneous vs. inhomogeneous coexistence of magnetic order and superconductivity probed by NMR in Co and K doped iron pnictides | In Ba(Fe0.95Co0.05)2As2 all of the 75As NMR intensity at the paramagnetic
resonance position vanishes abruptly below Tonset(SDW)=56 K, indicating that
magnetic (spin density wave) order is present in all of the sample volume,
despite bulk superconductivity below Tc=15 K. The two phases thus coexist
homogeneously at the... | 0906.3708v1 |
2009-06-26 | Differential stellar population models: how to reliably measure [Fe/H] and [alpha/Fe] in galaxies | We present differential stellar population models, which allow improved
determinations of the ages, iron and alpha-element abundances of old stellar
populations from spectral fitting. These new models are calibrated at solar
abundances using the predictions from classical, semi-empirical stellar
population models. We t... | 0906.5000v1 |
2009-06-29 | Upper critical fields of the 11-system iron-chalcogenide superconductor FeSe$_{0.25}$Te$_{0.75}$ | We have performed electrical resistivity measurements of a polycrystalline
sample of FeSe$_{0.25}$Te$_{0.75}$, which exhibits superconductivity at $T_{\rm
c} \sim 14$ K, in magnetic fields up to 55 T to determine the upper critical
field $\mu_{0}H_{\rm c2}$. In this compound, very large slopes of
$\mu_{0}H_{\rm c2}$ at... | 0906.5248v1 |
2009-06-30 | Fermi surface topology and low-lying quasiparticle dynamics of parent Fe$_{1+x}$Te/Se Superconductor by orbital-polarization resolved ARPES | We report the first photoemission study of Fe$_{1+x}$Te - the host compound
of the newly discovered iron-chalcogenide superconductors (maximum T$_c$ $\sim$
27K). Our results reveal a pair of nearly electron-hole compensated Fermi
pockets, strong Fermi velocity renormalization and an absence of a
spin-density-wave gap. ... | 0906.5392v1 |
2009-06-30 | Disorder-sensitive superconductivity in the iron silicide Lu$_2$Fe$_3$Si$_5$ studied by the Lu-site substitutions | We studied effect of non-magnetic and magnetic impurities on
superconductivity in Lu$_2$Fe$_3$Si$_5$ by small amount substitution of the Lu
site, which investigated structural, magnetic, and electrical properties of
non-magnetic (Lu$_{1-x}$Sc$_x$)$_2$Fe$_3$Si$_5$,
(Lu$_{1-x}$Y$_x$)$_2$Fe$_3$Si$_5$, and magnetic
(Lu$_{1... | 0906.5569v1 |
2009-07-01 | Chemical Compositions of Kinematically Selected Outer Halo Stars | Chemical abundances of 26 metal-poor dwarfs and giants are determined from
high-resolution and high signal-to-noise ratio spectra obtained with
Subaru/HDS. The sample is selected so that most of the objects have outer-halo
kinematics. Self-consistent atmospheric parameters were determined by an
iterative procedure base... | 0907.0076v2 |
2009-07-03 | Atomically-flat, chemically-stable, superconducting epitaxial thin film of iron-based superconductor, cobalt-doped BaFe$_2$As$_2$ | Epitaxial growth of Fe-based superconductors such as Co-doped SrFe$_2$As$_2$
(SrFe$_2$As$_2$:Co) was reported recently, but has still insufficient
properties for device application because they have rough surfaces and are
decomposed by reactions with water vapor in an ambient atmosphere. This letter
reports that epitax... | 0907.0666v1 |
2009-07-07 | Phase diagram of the PrFeAsO$_{1-x}$F$_{x}$ superconductor | The electronic phase diagram of PrFeAsO$_{1-x}$F$_{x}$ (0$\leq$x$\leq$0.225)
has been determined using synchrotron X-ray powder diffraction, magnetization
and resistivity measurements. The structural transition temperature is
suppressed from 154 K to $\approx$120 K and the magnetic phase transitions of
both iron and pr... | 0907.1308v1 |
2009-07-15 | Quark matter under strong magnetic fields in the su(3) Nambu-Jona-Lasinio Model | In the present work we use the mean field approximation to investigate quark
matter described by the su(3) Nambu-Jona-Lasinio model subject to a strong
magnetic field. We consider two cases: pure quark matter and quark matter in
beta-equilibrium possibly present in magnetars. The results are compared with
the ones obta... | 0907.2607v1 |
2009-07-15 | Driving and damping mechanisms in hybrid pressure-gravity modes pulsators | We study the energetic aspects of hybrid pressure-gravity modes pulsations.
The case of hybrid beta Cephei-SPB pulsators is considered with special
attention. In addition to the already known sensitivity of the driving
mechanism to the heavy elements mixture (mainly the iron abundance), we show
that the characteristics... | 0907.2636v1 |
2009-07-16 | Lattice distortion and magnetic quantum phase transition in CeFeAs(1-x)P(x)O | We use neutron scattering to show that replacing the larger arsenic with
smaller phosphorus in CeFeAs(1-x)P(x)O simultaneously suppresses the AF order
and orthorhombic distortion near x = 0.4, providing evidence for a magnetic
quantum critical point. Furthermore, we find that the pnictogen height in iron
arsenide is an... | 0907.2853v1 |
2009-07-17 | Phase diagram of CeFeAs$_{1-x}$P$_{x}$O obtained from electric resistivity, magnetization, and specific heat measurements | We performed a systematic study on the properties of CeFeAs$_{1-x}$P$_{x}$O
($0\leq x\leq 1$) by electrical resistivity, magnetization and specific heat
measurements. The c-axis lattice constant decreases significantly with
increasing P content, suggesting a remarkable chemical pressure. The Fe-3d
electrons show the en... | 0907.2961v2 |
2009-07-21 | Discrimination of mass hierarchy with atmospheric neutrinos at a magnetized muon detector | We have studied the mass hierarchy with atmospheric neutrinos considering the
muon energy and zenith angle of the event at the magnetized iron calorimeter
detector. For $\chi^2$ analysis we have migrated the number of events from
neutrino energy and zenith angle bins to muon energy and zenith angle bins
using the two-d... | 0907.3540v3 |
2009-07-21 | The Dependency of the Cepheid Period-Luminosity Relation on Chemical Composition | The dependency of the Cepheid Period-Luminosity Relation on chemical
composition at different wavelengths is assessed via direct detailed abundance
analysis of Galactic and Magellanic Cepheids, as derived from high resolution,
high signal-to-noise spectra. Our measurements span one order of magnitude in
iron content an... | 0907.3655v2 |
2009-07-23 | Prospects of measuring the leptonic CP phase with atmospheric neutrinos | We have studied the prospects of measuring the CP violating phase with
atmospheric neutrinos at a large magnetized iron calorimeter detector
considering the muons (directly measurable) of the neutrino events generated by
a MonteCarlo event generator Nuance. The effect of $\theta_{13}$ and
$\delta_{CP}$ appears dominant... | 0907.3978v2 |
2009-07-24 | In-situ fabrication of cobalt-doped SrFe2As2 thin films by using pulsed laser deposition with excimer laser | The remarkably high superconducting transition temperature and upper critical
field of iron(Fe)-based layered superconductors, despite ferromagnetic material
base, open the prospect for superconducting electronics. However, success in
superconducting electronics has been limited because of difficulties in
fabricating h... | 0907.4227v1 |
2009-07-31 | A new surface parameter for composition studies at high energies | A new family of parameters intended for composition studies is presented.
They make exclusive use of surface data combining the information from the
total signal at each triggered detector and the array geometry. We perform an
analytical study of these composition estimators in order to assess their
reliability, stabil... | 0907.5480v1 |
2009-07-31 | The cleavage surface of the BaFe_(2-x)Co_(x)As_(2) and Fe_(y)Se_(1-x)Te_(x) superconductors: from diversity to simplicity | We elucidate the termination surface of cleaved single crystals of the
BaFe_(2-x)Co_(x)As_(2) and Fe_(y)Se_(1-x)Te_(x) families of the high
temperature iron based superconductors. By combining scanning tunneling
microscopic data with low energy electron diffraction we prove that the
termination layer of the Ba122 syste... | 0907.5544v1 |
2009-07-31 | Magnetism and superconductivity in single crystals $Eu_{1-x}Sr_xFe_{2-y}Co_{y}As_2$ | We systematically studied the transport properties of single crystals of
$Eu_{1-x}Sr_xFe_{2-y}$Co$_{y}As_2$. Co doping can suppress the spin-density
wave (SDW) ordering and induces a superconducting transition, but a resistivity
reentrance due to the antiferromagnetic ordering of $Eu^{2+}$ spins is
observed, indicating... | 0907.5547v1 |
2009-08-05 | ^{31}P and ^{75}As NMR evidence for a residual density of states at zero energy in superconducting BaFe_2(As_{0.67}P_{0.33})_2 | ^{31}P and ^{75}As NMR measurements were performed in superconducting
BaFe_2(As_{0.67}P_{0.33})_2 with T_c = 30 K. The nuclear-spin-lattice
relaxation rate T_1^{-1} and the Knight shift in the normal state indicate the
development of antiferromagnetic fluctuations, and T_1^{-1} in the
superconducting (SC) state decreas... | 0908.0625v2 |
2009-08-05 | Krylov implementation of the hybridization expansion impurity solver and application to 5-orbital models | We present an implementation of the hybridization expansion impurity solver
which employs sparse matrix exact-diagonalization techniques to compute the
time evolution of the local Hamiltonian. This method avoids computationally
expensive matrix-matrix multiplications and becomes advantageous over the
conventional imple... | 0908.0681v2 |
2009-08-12 | The Inner Rim Structures of Protoplanetary Discs | The inner boundary of protoplanetary discs is structured by the dramatic
opacity changes at the transition from the dust-containing to a dust-free zone.
This paper explores the variety and limits of inner rim structures in passively
heated dusty discs. For this study, we implemented detailed sublimation physics
in a fa... | 0908.1692v3 |
2009-08-20 | Evidence for Nodal superconductivity in Sr$_{2}$ScFePO$_{3}$ | Point contact Andreev reflection spectra have been taken as a function of
temperature and magnetic field on the polycrystalline form of the newly
discovered iron-based superconductor Sr2ScFePO3. A zero bias conductance peak
which disappears at the superconducting transition temperature, dominates all
of the spectra. Da... | 0908.2902v2 |
2009-08-21 | Magnetic structure of EuFe2As2 determined by single crystal neutron diffraction | Among various parent compounds of iron pnictide superconductors, EuFe2As2
stands out due to the presence of both spin density wave of Fe and
antiferromagnetic ordering (AFM) of the localized Eu2+ moment. Single crystal
neutron diffraction studies have been carried out to determine the magnetic
structure of this compoun... | 0908.3142v1 |
2009-08-24 | The two-dimensional frustrated Heisenberg model on the orthorhombic lattice | We discuss new high-field magnetization data recently obtained by Tsirlin et
al. for layered vanadium phosphates in the framework of the square-lattice
model. Our predictions for the saturation fields compare exceptionally well to
the experimental findings, and the strong bending of the curves below
saturation agrees v... | 0908.3442v1 |
2009-09-02 | A study of nuclear effect in $F_3$ structure function in the deep inelastic $ν(\barν)$ reactions in nuclei | We study nuclear effect in the $F^A_3(x)$ structure function in the deep
inelastic neutrino reactions on iron by taking into account Fermi motion,
binding, target mass correction, shadowing and anti-shadowing corrections.
Calculations have been done in a local density approximation using relativistic
nuclear spectral f... | 0909.0360v1 |
2009-09-02 | Nuclear EMC Effect in a Statistical Model | A simple statistical model in terms of light-front kinematic variables is
used to explain the nuclear EMC effect in the range $x \in [0.2,~0.7]$, which
was constructed by us previously to calculate the parton distribution functions
(PDFs) of the nucleon. Here, we treat the temperature $T$ as a parameter of the
atomic n... | 0909.0454v1 |
2009-09-03 | Observation of Dirac Cone Electronic Dispersion in BaFe2As2 | We performed an angle-resolved photoemission spectroscopy study of BaFe2As2,
which is the parent compound of the so-called 122 phase of the iron-pnictide
high-temperature superconductors. We reveal the existence of a Dirac cone in
the electronic structure of this material below the spin-density-wave
temperature, which ... | 0909.0574v1 |
2009-09-04 | Unconventional electronic reconstruction in undoped (Ba,Sr)Fe$_2$As$_2$ across the spin density wave transition | Through a systematic high resolution angle-resolved photoemission study of
the iron pnictide compounds (Ba,Sr)Fe$_2$As$_2$, we show that the electronic
structures of these compounds are significantly reconstructed across the spin
density wave ordering, which cannot be described by a simple folding scenario
of conventio... | 0909.0831v1 |
2009-09-04 | Inelastic X-ray Scattering Study of superconducting SmFeAs(O$_{1-x}$F$_{y}$) Single Crystals: Evidence for Strong Momentum-Dependent Doping-Induced Renormalizations of Optical Phonons | We report inelastic x-ray scattering experiments on the lattice dynamics in
SmFeAsO and superconducting SmFeAsO$_{0.6}$F$_{0.35}$ single crystals.
Particular attention was paid to the dispersions along the [100] direction of
three optical modes close to 23 meV, polarized out of the FeAs planes.
Remarkably, two of these... | 0909.0913v2 |
2009-09-04 | Intrinsic pinning on structural domains in underdoped single crystals of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ | Critical current density was studied in single crystals of
Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ for the values of $x$ spanning the entire doping
phase diagram. A noticeable enhancement was found for slightly underdoped
crystals with the peak at $x = 0.058$. Using a combination of polarized-light
imaging, x-ray diffraction an... | 0909.0923v3 |
2009-09-04 | X-raying the Winds of Luminous Active Galaxies | We briefly describe some recent observational results, mainly at X-ray
wavelengths, on the winds of luminous active galactic nuclei (AGNs). These
winds likely play a significant role in galaxy feedback. Topics covered include
(1) Relations between X-ray and UV absorption in Broad Absorption Line (BAL)
and mini-BAL quas... | 0909.0958v1 |
2009-09-11 | The double life of electrons in magnetic iron pnictides, as revealed by NMR | We present a phenomenological, two-fluid approach to understanding the
magnetic excitations in Fe pnictides, in which a paramagnetic fluid with
gapless, incoherent particle-hole excitations coexists with an
antiferromagnetic fluid with gapped, coherent spin wave excitations. We show
that this two-fluid phenomenology pr... | 0909.2207v4 |
2009-09-12 | Nuclear effects in neutrino-nucleus DIS | We explain the current status of nuclear parton distribution functions in
connection with neutrino-nucleus interactions. Neutrino deep inelastic
scattering (DIS) measurements have been done for heavy nuclear targets such as
iron and lead. In order to extract structure functions of the nucleon, one
needs to remove nucle... | 0909.2329v1 |
2009-09-15 | Theory of Andreev reflection in a two-orbital model of iron-pnictide superconductors | A recently developed theory for the problem of Andreev reflection between a
normal metal (N) and a multiband superconductor (MBS) assumes that the incident
wave from the normal metal is coherently transmitted through several bands
inside the superconductor. Such splitting of the probability amplitude into
several chann... | 0909.2826v1 |
2009-09-16 | Electronic band structure, phonon spectrum, and elastic properties of LaOFeAs | We present results of ab-initio calculations of the electronic band
structure, lattice dynamical properties, and elastic constants of LaOFeAs, the
parent compound of the recently discovered superconducting iron-oxypnictide
(LaO1-xFxFeAs). The total and partial electronic density of states (EDOS) of
the undoped LaOFeAs ... | 0909.2914v2 |
2009-09-16 | Calculation of stellar electron-capture cross sections on nuclei based on microscopic Skyrme functionals | A fully self-consistent microscopic framework for evaluation of nuclear
weak-interaction rates at finite temperature is introduced, based on Skyrme
functionals. The single-nucleon basis and the corresponding thermal occupation
factors of the initial nuclear state are determined in the finite-temperature
Skyrme Hartree-... | 0909.3070v1 |
2009-09-17 | Bulk electronic structure of optimally doped Ba(Fe$_{1-x}$Co$_{x}$)$_2$As$_2$ | We report high-resolution, bulk Compton scattering measurements unveiling the
Fermi surface of an optimally-doped iron-arsenide superconductor,
Ba(Fe$_{0.93}$Co$_{0.07}$)$_2$As$_2$. Our measurements are in agreement with
first-principles calculations of the electronic structure, revealing both the
$X$-centered electron... | 0909.3194v2 |
2009-09-25 | Modelling hybrid Beta Cephei/SPB pulsations: Gamma Pegasi | Recent photometric and spectroscopic observations of the hybrid variable
Gamma Pegasi (Handler et al. 2009, Handler 2009) revealed 6 frequencies of the
SPB type and 8 of the Beta Cep type pulsations. Standard seismic models, which
have been constructed with OPAL (Iglesias & Rogers 1996) and OP (Seaton 2005)
opacities b... | 0909.4643v1 |
2009-09-29 | Weak anisotropy of the superconducting upper critical field in Fe1.11Te0.6Se0.4 single crystals | We have determined the resistive upper critical field Hc2 for single crystals
of the superconductor Fe1.11Te0.6Se0.4 using pulsed magnetic fields of up to
60T. A rather high zero-temperature upper critical field of mu0Hc2(0) approx
47T is obtained, in spite of the relatively low superconducting transition
temperature (... | 0909.5328v1 |
2009-09-30 | He and Ne ages of large presolar silicon carbide grains: Solving the recoil problem | Knowledge about the age of presolar grains provides important insights into
Galactic chemical evolution and the dynamics of grain formation and destruction
processes in the Galaxy. Determination from the abundance of cosmic ray
interaction products is straightforward, but in the past has suffered from
uncertainties in ... | 0909.5532v1 |
2009-10-01 | Pressure-driven phase transitions in correlated systems | Motivated by recent experimental measurements on pressure-driven phase
transitions in Mott-insulators as well as the new iron pnictide
superconductors, we show that first principles Car-Parrinello molecular
dynamics calculations are a powerful method to describe the microscopic origin
of such transitions. We present re... | 0910.0158v1 |
2009-10-05 | Isotope shifts and hyperfine structure of the Fe I 372 nm resonance line | We report measurements of the isotope shifts of the $3d^64s^2 a ^5D_4 -
3d^64s4p z ^5F_5^o$ Fe I resonance line at 372 nm between all four stable
isotopes $^{54}$Fe, $^{56}$Fe, $^{57}$Fe, and $^{58}$Fe, as well as the
complete hyperfine structure of that line for $^{57}$Fe, the only stable
isotope having a non-zero nuc... | 0910.0479v1 |
2009-10-05 | First-principles thermal equation of state and thermoelasticity of hcp Fe at high pressures | We investigate the equation of state and elastic properties of hcp iron at
high pressures and high temperatures using first principles linear response
linear-muffin-tin-orbital method in the generalized-gradient approximation. We
calculate the Helmholtz free energy as a function of volume, temperature, and
volume-conse... | 0910.0884v1 |
2009-10-06 | Band and momentum dependent electron dynamics in superconducting ${\rm Ba(Fe_{1-x}Co_{x})_2As_2}$ as seen via electronic Raman scattering | We present details of carrier properties in high quality ${\rm
Ba(Fe_{1-x}Co_{x})_2As_2}$ single crystals obtained from electronic Raman
scattering. The experiments indicate a strong band and momentum anisotropy of
the electron dynamics above and below the superconducting transition
highlighting the importance of compl... | 0910.0898v2 |
2009-10-09 | On the influence of high energy electron populations on metal abundance estimates in galaxy groups and clusters | Spectral line emissivities have usually been calculated for a Maxwellian
electron distribution. But many theoretical works on galaxy groups and clusters
and on the solar corona suggest to consider modified Maxwellian electron
distribution functions to fit observed X-ray spectra. Here we examine the
influence of high en... | 0910.1640v1 |
2009-10-14 | Electron correlation and spin density wave order in iron pnictides | We study the correlation effects on the electronic structure and spin density
wave order in Fe-pnictides. Using the multiorbital Hubbard model and Gutzwiller
projection, we show that nonperturbative correlation effects are essential to
stabilize the metallic spin density wave phase for the intermediate correlation
stre... | 0910.2707v2 |
2009-10-15 | Single vortex structure in two models of iron pnictide $s^\pm$ superconductivity | The structure of a single vortex in a FeAs superconductor is studied in the
framework of two formulations of superconductivity for the recently proposed
sign-reversed $s$ wave ($s^\pm$) scenario: {\it (i)} a continuum model taking
into account the existence of an electron and a hole band with a repulsive
local interact... | 0910.2879v1 |
2009-10-19 | New approach to primary mass composition analysis with simultaneous use of ground and fluorescence detectors data | We study the possibility to reconstruct primary mass composition with the use
of combinations of basic shower characteristics, measured in hybrid
experiments, such as depth of shower maximum from fluorescence side and signal
in water Cherenkov tanks or in plastic scintillators from the ground side. To
optimize discrimi... | 0910.3520v1 |
2009-10-22 | About the strength of correlation effects in the electronic structure of iron | The strength of electronic correlation effects in the spin-dependent
electronic structure of ferromagnetic bcc Fe(110) has been investigated by
means of spin and angle-resolved photoemission spectroscopy. The experimental
results are compared to theoretical calculations within the three-body
scattering approximation an... | 0910.4360v1 |
2009-10-29 | Surprising Metallicity of a Newly Discovered M79 Post-AGB Star | A detailed chemical composition analysis based on a high-resolution
(R=35,000) CCD spectrum is presented for a newly discovered post-AGB star in
the globular cluster M79 for the first time. The elemental abundance results of
M79 Post-AGB star are found to be [C/Fe]=-0.7, [O/Fe]=+1.4, [alpha-
process/Fe]=0.5, and [s-pro... | 0910.5567v1 |
2009-10-29 | Simulation of a flux emergence event and comparison with observations by Hinode | We study the observational signature of flux emergence in the photosphere
using synthetic data from a 3D MHD simulation of the emergence of a twisted
flux tube. Several stages in the emergence process are considered. At every
stage we compute synthetic Stokes spectra of the two iron lines Fe I 6301.5
{\AA} and Fe I 630... | 0910.5737v1 |
2009-11-04 | Solar-like oscillations in massive main-sequence stars. I. Asteroseismic signatures of the driving and damping regions | Motivated by the recent detection of stochastically excited modes in the
massive star V1449 Aql (Belkacem et al., 2009b), already known to be a $\beta$
Cephei, we theoretically investigate the driving by turbulent convection. By
using a full non-adiabatic computation of the damping rates, together with a
computation of... | 0911.0908v1 |
2009-11-05 | Ultra-High Energy Cosmic-Ray Acceleration in the Jet of Centaurus A | We evaluate the achievable maximum energy of nuclei diffusively accelerated
by shock wave in the jet of Cen A, based on an updated model involving the
stochastic magnetic fields that are responsible for recent synchrotron X-ray
measurements. For the maximum energy analysis, conceivable energy constraints
from spatiotem... | 0911.0921v1 |
2009-11-09 | Role of dipole-dipole interactions in multiple quantum transitions in magnetic nanoparticles | In order to better understand the origin of multiple quantum transitions
observed in superparamagnetic nanoparticles, electron magnetic resonance (EMR)
studies have been performed on iron oxide nanoparticles assembled inside the
anodic alumina membrane. The positions of both the main resonance and
"forbidden" (double-q... | 0911.1752v1 |
2009-11-11 | Gravitational Lensing by Black Holes | We review the theoretical aspects of gravitational lensing by black holes,
and discuss the perspectives for realistic observations. We will first treat
lensing by spherically symmetric black holes, in which the formation of
infinite sequences of higher order images emerges in the clearest way. We will
then consider the... | 0911.2187v2 |
2009-11-13 | An Unusually Fast-Evolving Supernova | Analyses of supernovae (SNe) have revealed two main types of progenitors:
exploding white dwarfs and collapsing massive stars. We present SN2002bj, which
stands out as different from any SN reported to date. Its light curve rises and
declines very rapidly, yet reaches a peak intrinsic brightness greater than -18
mag. A... | 0911.2699v1 |
2009-11-16 | Effects of nematic fluctuations on the elastic properties of iron arsenide superconductors | We demonstrate that the changes in the elastic properties of the FeAs
systems, as seen in our resonant ultrasound spectroscopy data, can be naturally
understood in terms of fluctuations of emerging nematic degrees of freedom.
Both the softening of the lattice in the normal, tetragonal phase as well as
its hardening in ... | 0911.3084v2 |
2009-11-18 | Thermonuclear explosions of rapidly rotating white dwarfs - II. Detonations | Context: Superluminous type Ia supernovae (SNe Ia) may be explained by
super-Chandrasekhar-mass explosions of rapidly rotating white dwarfs (WDs). In
a preceding paper, we showed that the deflagration scenario applied to rapidly
rotating WDs generates explosions that cannot explain the majority of SNe Ia.
Aims: Rotatio... | 0911.3545v1 |
2009-11-18 | Suzaku broadband spectroscopy of Swift J1753.5-0127 in the Low-Hard State | We present Suzaku observations of the Galactic black hole candidate Swift
J1753.5-0127 in the low-hard state. The broadband coverage of Suzaku enables us
to detect the source over the energy range 0.6 -- 250 keV. The broadband
spectrum (2 -- 250 keV) is found to be consistent with a simple power-law
(gamma \sim 1.63). ... | 0911.3642v1 |
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