publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2011-03-30 | Biaxially textured cobalt-doped BaFe2As2 films with high critical current density over 1 MA/cm2 on MgO-buffered metal-tape flexible substrates | High critical current densities (Jc) > 1 MA/cm2 were realized in cobalt-doped
BaFe2As2 (BaFe2As2:Co) films on flexible metal substrates with
biaxially-textured MgO base-layers fabricated by an ion-beam assisted
deposition technique. The BaFe2As2:Co films showed small in-plane crystalline
misorientations (delta fai BaFe... | 1103.5815v2 |
2011-04-04 | Epitaxial growth of FeSe$_{0.5}$Te$_{0.5}$ thin films on CaF$_2$ substrates with high critical current density | In-situ epitaxial growth of FeSe$_{0.5}$Te$_{0.5}$ thin films is demonstrated
on a non-oxide substrate CaF$_2$. Structural analysis reveals that compressive
stress is moderately added to 36-nm thick FeSe$_{0.5}$Te$_{0.5}$, which pushes
up the critical temperature above 15 K, showing higher values than that of bulk
crys... | 1104.0477v2 |
2011-04-04 | The NLTE Barium Abundance in Dwarf Stars in the Metallicity Range of -1 < [Fe/H] < +0.3 | We present the results of determination of the barium abundance considering
the non-LTE (NLTE) effects in 172 dwarf stars in the metallicity range of -1<
[Fe/H] <+0.3, assigned to different Galactic substructures by kinematic
criteria. We used a model of the Ba atom with 31 levels of Ba I and 101 levels
of Ba II. The a... | 1104.0534v1 |
2011-04-05 | Incommensurate spin-density wave order in electron-doped BaFe2As2 superconductors | Neutron diffraction studies of Ba(Fe[1-x]Co[x])2As2 reveal that commensurate
antiferromagnetic order gives way to incommensurate magnetic order for Co
compositions between 0.056 < x < 0.06. The incommensurability has the form of a
small transverse splitting (0, +-e, 0) from the nominal commensurate
antiferromagnetic pr... | 1104.0717v1 |
2011-04-08 | Magnetic nanocomposites at microwave frequencies | Most conventional magnetic materials used in the electronic devices are
ferrites, which are composed of micrometer-size grains. But ferrites have small
saturation magnetization, therefore the performance at GHz frequencies is
rather poor. That is why functionalized nanocomposites comprising magnetic
nanoparticles (e.g.... | 1104.1535v1 |
2011-04-11 | Collinear to Anti-collinear Quantum Phase Transition by Vacancies | We study static vacancies in the collinear magnetic phase of a frustrated
Heisenberg $J_1$-$J_2$ model. It is found that vacancies can rapidly suppress
the collinear antiferromagnetic state (CAFM)and generate a new magnetic phase,
an anti-collinear magnetic phase (A-CAFM), due to magnetic frustration. We
investigate th... | 1104.1848v2 |
2011-04-12 | Reply to "Comment on 'Isotope effect in multi-band and multi-channel attractive systems and inverse isotope effect in iron-based superconductors'" | The Comment insists on the following: in our model it is assumed that the
effective interactions have specific energy ranges within the single band with
a cutoff at \omega_1 for the phononic part and a range from \omega_1 to
\omega_2 in the AF channel. Our reply is that we assume that V_i(k,k')\neq 0 if
|\xi_k|<\omega_... | 1104.2146v1 |
2011-03-26 | Parametrization for Cherenkov light lateral distribution function in Extensive Air Showers | The simulation of the Cherenkov light lateral distribution function (LDF) in
Extensive Air Showers (EAS) was perfomed with the CORSIKA code in the energy
range 10^13-10^16 eV for configuration of the Tunka-25 EAS array. On the basis
of this simulation we obtained sets of approximating functions for primary
protons, iro... | 1104.2510v1 |
2011-04-15 | The effect of hydrogen on the magnetic properties of FeV superlattice | The electronic and magnetic structures of a hydrogenated and hydrogen free
superlattice of 3 iron monolayers and 9 vanadium monolayers are studied using
the first principle full-potential augmented-plane-wave method as implemented
in WIEN2k package. The volume, the total energy and the magnetic moments of the
system ar... | 1104.2965v1 |
2011-04-18 | A new composition-sensitive parameter for Ultra-High Energy Cosmic Rays | A new family of parameters intended for composition studies in cosmic ray
surface array detectors is proposed. The application of this technique to
different array layout designs has been analyzed. The parameters make exclusive
use of surface data combining the information from the total signal at each
triggered detect... | 1104.3399v1 |
2011-04-22 | Modelling the Broad-band Spectra of MCG-6-30-15 with a Relativistic Reflection Model | The spectrum of the bright Seyfert I galaxy MCG-6-30-15 shows a broad Fe
K-alpha emission line, generally interpreted to originate very close to the
central black hole which must then have a high spin. The observed X-ray
variability is driven by a powerlaw component, with little variability found in
the iron line energ... | 1104.4483v1 |
2011-04-27 | Study of the X-ray/gamma source AX J1910.7+0917 and three newly discovered INTEGRAL sources | AX J1910.7+0917 is a still unidentified source discovered with ASCA and
observed more recently with IBIS/ISGRI, mainly noticeable for its rather hard
spectrum. We analyzed all the public available data on this source, and we took
advantage of the recent improvements performed in the INTEGRAL data analysis
software to f... | 1104.5102v1 |
2011-04-28 | Electronic inhomogeneity in a Kondo lattice | Inhomogeneous electronic states resulting from entangled spin, charge, and
lattice degrees of freedom are hallmarks of strongly correlated electron
materials; such behavior has been observed in many classes of d-electron
materials, including the high-Tc copper-oxide superconductors, manganites, and
most recently the ir... | 1104.5457v1 |
2011-04-29 | Evolution of correlation strength in KxFe(2-y)Se2 superconductor doped with S | We report the evolution of thermal transport properties of iron-based
superconductor K$_x$Fe$_{2-y}$Se$_2$ with sulfur substitution at Se sites.
Sulfur doping suppresses the superconducting $T_c$ as well as the Seebeck
coefficient. The Seebeck coefficient of all crystals in the low temperature
range can be described ve... | 1104.5711v1 |
2011-04-30 | Magnetic hydrogels derived from polysaccharides with improved specific power absorption: potential devices for remotely triggered drug delivery | We report on novel ferrogels derived from polysaccharides (sodium alginate
and chitosan) with embedded iron oxide nanoparticles synthesized in situ and
their combination with thermally responsive poly (N-isopropylacrylamide) for
externally-driven drug release using AC magnetic fields. Samples were
characterized by Rama... | 1105.0075v1 |
2011-05-11 | Systematics of the temperature-dependent inter-plane resistivity in Ba(Fe$_{1-x}$T$_x$)$_2$As$_2$ with T= Rh, Ni, and Pd | Temperature-dependent inter-plane resistivity, $\rho_c(T)$, was measured
systematically as a function of transition metal substitution in the
iron-arsenide superconductors Ba(Fe$_{1-x}$T$_x$)$_2$As$_2$, $T$= Ni, Pd, Rh.
The data are compared with the behavior found in
Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, revealing resistive... | 1105.2277v1 |
2011-05-13 | Scaling of nascent nodes in extended s-wave superconductors | We analyze the low-energy properties of superconductors near the onset of
accidental nodes, i.e. zeroes of the gap function not enforced by symmetry. The
existence of such nodes has been motivated by recent experiments suggesting a
transition between nodeless and nodal superconductivity in iron-based
compounds. We find... | 1105.2785v2 |
2011-05-17 | Superconductivity and ferromagnetism in EuFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ | Superconductivity and ferromagnetism are two antagonistic cooperative
phenomena, which makes it difficult for them to coexist. Here we demonstrate
experimentally that they do coexist in EuFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ with
$0.2\leq x\leq0.4$, in which superconductivity is associated with Fe-3$d$
electrons and ferro... | 1105.3255v1 |
2011-05-17 | Effective Ex-Situ Fabrication of F-Doped SmFeAsO Wire for High Transport Critical Current Density | We demonstrate the fabrication of superconducting SmFeAsO1-xFx (Sm-1111)
wires by using the ex-situ powder-in-tube technique. Sm-1111 powder and a
binder composed of SmF3, samarium arsenide, and iron arsenide were used to
synthesize the superconducting core. Although the F content of Sm-1111 is
reduced in the process o... | 1105.3342v2 |
2011-05-19 | High energy pseudogap and its evolution with doping in Fe-based superconductors as revealed by optical spectroscopy | We report optical spectroscopic measurements on electron- and hole-doped
BaFe2As2. We show that the compounds in the normal state are not simple metals.
The optical conductivity spectra contain, in addition to the free carrier
response at low frequency, a temperature-dependent gap-like suppression at
rather high energy... | 1105.3939v1 |
2011-05-20 | Neutrino Probes of the Nature of Light Dark Matter | Dark matter particles gravitationally trapped inside the Sun may annihilate
into Standard Model particles, producing a flux of neutrinos. The prospects of
detecting these neutrinos in future multi-\kton{} neutrino detectors designed
for other physics searches are explored here. We study the capabilities of a
34/100 \kt... | 1105.4077v2 |
2011-05-26 | Phosphor induced significant hole-doping in ferropnictide superconductor BaFe2(As(1-x)Px)2 | The superconductivity in high temperature superconductors ordinarily arises
when doped with hetero-valent ions that introduce charge carriers. However, in
ferropnictides, "iso-valent" doping, which is generally believed not to
introduce charge carriers, can induce superconductivity as well. Moreover,
unlike other ferro... | 1105.5242v1 |
2011-05-27 | Orbitally resolved lifetimes in Ba(Fe0.92Co0.08)2As2 measured by ARPES | Despite many ARPES investigations of iron pnictides, the structure of the
electron pockets is still poorly understood. By combining ARPES measurements in
different experimental configurations, we clearly resolve their elliptic shape.
Comparison with band calculation identify a deep electron band with the dxy
orbital an... | 1105.5604v2 |
2011-05-31 | Micromagnetic study of flux-closure states in Fe dots using quantitative Lorentz Microscopy | A micromagnetic study of epitaxial micron-sized iron dots is reported through
the analysis of Fresnel contrast in Lorentz Microscopy. Their use is reviewed
and developed through analysis of various magnetic structures in such dots.
Simple Landau configuration is used to investigate various aspects of
asymmetric Bloch d... | 1105.6295v2 |
2011-06-05 | Novel Insulating Magnetism in Vacancy-Ordered K2Fe4Se5 | We unveil the novel physical origin of the insulating block checkerboard
antiferromagnetism in vacancy-ordered K2Fe4Se5. Our first-principles electronic
structure analysis reveals its incompatibility with a simple Fermi-surface
nesting or Mott insulator scenario, and suggests the picture of coexisting
itinerant and loc... | 1106.0881v2 |
2011-06-06 | Correlation of high temperature X-ray photoemission spectral features and conductivity of epitaxially strained (La0.8Sr0.2)0.95Ni0.2Fe0.8O3/SrTiO3(110) | Reversible and irreversible discontinuities at around 573 K and 823 K in the
electric conductivity of a strained 175 nm thin film of
(La0.8Sr0.2)0.95Ni0.2Fe0.8O3-{\delta} grown by pulsed laser deposition on
SrTiO3 (110) are reflected by valence band changes as monitored in
photoemission and oxygen K-edge x-ray absorpti... | 1106.1024v1 |
2011-06-06 | Fe-resonant valence band photoemission and oxygen NEXAFS study on La1-xSrxFe0.75Ni0.25O3-δ | Iron resonant valance band photoemission spectra of Sr substituted
LaFe0.75Ni0.25 O3-{\delta} have been recorded across the Fe 2p - 3d absorption
threshold to obtain Fe specific spectral information on the 3d projected
partial density of states. Comparison with La1-xSrxFeO3 resonant VB PES
literature data suggests that... | 1106.1086v1 |
2011-06-07 | Analysis of interdiffusion between SmFeAsO0.92F0.08 and metals for ex situ fabrication of superconducting wire | We demonstrate the fabrication of superconducting SmFeAsO1-xFx (Sm-1111)
wires by using the ex-situ powder-in-tube technique. Sm-1111 powder and a
binder composed of SmF3, samarium arsenide, and iron arsenide were used to
synthesize the superconducting core. Although the F content of Sm-1111 is
reduced in the process o... | 1106.1328v2 |
2011-06-11 | Fish-tail and vortex dynamics in Ni doped iron-pnictide BaFe{1.82}Ni_{0.18}As_2 | We study the vortex-dynamics of a BaFe{1.82}Ni_{0.18}As_2 crystal with Tc = 8
K, by measuring flux-creep over the second magnetisation (or fish-tail) peak
for both H//c-axis and H//ab planes. Magnetic relaxation data show an
anomalously long initial stage of relaxation, lasting approximately10 minutes
for H//c-axis and... | 1106.2248v2 |
2011-06-17 | A Three-Dimensional Tight-Binding Model and Magnetic Instability of KFe2e2 | For a newly discovered iron-based high T_c superconducting parent material
KFe2Se2, we present an effective three-dimensional five-orbital tight-binding
model by fitting the band structures. The three t2g-symmetry orbitals of the
five Fe 3d orbitals mainly contribute to the electron-like Fermi surface, in
agreement wit... | 1106.3485v1 |
2011-06-21 | Antiferromagnetic Spin Fluctuations and Unconventional Nodeless Superconductivity in an Iron-based New Superconductor (Ca_4Al_2O_{6-y})(Fe_2As_2):75As-NQR Study | We report 75As-nuclear quadrupole resonance (NQR) studies on
(Ca_4Al_2O_{6-y})(Fe_2As_2) with Tc=27K, which unravel unique normal-state
properties and point to unconventional nodeless superconductivity (SC).
Measurement of nuclear-spin-relaxation rate 1/T_1 has revealed a significant
development of two dimensional (2D)... | 1106.4105v1 |
2011-06-22 | Evidence for conventional superconductivity in SrPd2Ge2 | Electronic structure of SrPd2Ge2 single crystals is studied by angle-resolved
photoemission spectroscopy (ARPES), scanning tunneling spectroscopy (STS) and
band-structure calculations within the local-density approximation (LDA). The
STS measurements show single s-wave superconducting energy gap \Delta(0) = 0.5
meV. Ph... | 1106.4585v1 |
2011-06-26 | Anisotropic two-orbital Hubbard model: single-site versus cluster dynamical mean-field theory | The anisotropic two-orbital Hubbard model with different bandwidths and
degrees of frustration in each orbital is investigated in the framework of both
single-site dynamical mean-field theory (DMFT) as well as its cluster extension
(DCA) for clusters up to four sites combined with a continuous-time quantum
Monte Carlo ... | 1106.5255v1 |
2011-06-27 | Comment on "Infrared signature of the superconducting gap symmetry in iron-arsenide superconductors", Y. M. Dai et al. arXiv:1106.4430 | Y. M. Dai et al. in their recent work arXiv:1106.4430 presented a
reflectivity study of the in-plance optical conductivity of a
$\textrm{Ba}_{0.6}\textrm{K}_{0.4}\textrm{Fe}_2\textrm{As}_2$ (BKFA)
superconductor with $T_{\textrm{c}}\approx39K$. The single crystals used in
this study are of high quality and the measurem... | 1106.5343v1 |
2011-06-27 | Nodal superconductivity in Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ induced by isovalent Ru substitution | We present the ultra-low-temperature heat transport study of an iron-based
superconductor Ba(Fe$_{0.64}$Ru$_{0.36}$)$_2$As$_2$ ($T_c$ = 20.2 K), in which
the superconductivity is induced by isovalent Ru substitution. In zero field we
find a large residual linear term $\kappa_0/T$, more than 40% of the
normal-state valu... | 1106.5417v2 |
2011-06-29 | Suzaku Discovery of a Hard Component Varying Independently of the Power-Law Emission in MCG-6-30-15 | Focusing on hard X-ray variability, we reanalyzed Suzaku data of Type I
Seyfert galaxy MCG-6-30-15 obtained in 2006. Intensity-sorted spectroscopy and
a principal component analysis consistently revealed a very hard component that
varies independently of the dominant power-law emission. Although the exact
nature of thi... | 1106.5872v1 |
2011-07-02 | Nanoscale phase separation in the iron chalcogenide superconductor K0.8Fe1.6Se2 as seen via scanning nanofocused x-ray diffraction | Advanced synchrotron radiation focusing down to a size of 300 nm has been
used to visualize nanoscale phase separation in the K0.8Fe1.6Se2
superconducting system using scanning nanofocus single-crystal X-ray
diffraction. The results show an intrinsic phase separation in K0.8Fe1.6Se2
single crystals at T< 520 K, reveali... | 1107.0412v2 |
2011-07-03 | Linear decrease of critical temperature with increasing Zn substitution in the iron-based superconductor BaFe1.89-2xZn2xCo0.11As2 | The nonmagnetic impurity effect is studied on the Fe-based BaFe1.89Co0.11As2
superconductor (Tc = 25 K) with Zn substitution for Fe up to 8 at. %, which is
achieved by means of high-pressure and high-temperature heating. Tc decreases
almost linearly with increasing the Zn content and disappears at ~8 atomic %,
being di... | 1107.0423v1 |
2011-07-04 | London Penetration Depth in Iron - based Superconductors | Measurements of London penetration depth are a sensitive tool to study
multi-band superconductivity and it has provided several important insights to
the behavior of Fe-based superconductors. We first briefly review the
"experimentalist - friendly" self-consistent Eilenberger model that relates the
measurable superflui... | 1107.0675v1 |
2011-07-04 | Enhancement of the Superconducting Transition Temperature under Pressure in Rare-Earth Doped Ca$_{1-x}$La$_x$Fe$_2$As$_2$ (x=0.27) | We report measurements of the pressure dependence of the superconducting
transition temperature T_c in single crystal samples of the rare-earth doped
superconductor Ca$_{0.73}$La$_{0.27}$Fe$_2$As$_2$. We track T_c with two
techniques, via in-plane resistivity measurements and with a resonant tunnel
diode oscillator cir... | 1107.0689v1 |
2011-07-05 | Massless Leggett Mode in Three-band Superconductors with Time-Reversal-Symmetry Breaking | The Leggett mode associated with out-of-phase oscillations of superconducting
phase in multi-band superconductors usually is heavy due to the interband
coupling, which makes its excitation and detection difficult. We report on the
existence of a massless Leggett mode in three-band superconductors with
time-reversal-sym... | 1107.0814v2 |
2011-07-05 | Evidence for filamentary superconductivity nucleated at antiphase domain walls in antiferromagnetic CaFe$_2$As$_2$ | Resistivity, magnetization and microscopic $^{75}$As nuclear magnetic
resonance (NMR) measurements in the antiferromagnetically ordered state of the
iron-based superconductor parent material CaFe$_2$As$_2$ exhibit anomalous
features that are consistent with the collective freezing of domain walls.
Below $T^*\approx 10$... | 1107.0904v2 |
2011-07-07 | 56Ni, Explosive Nucleosynthesis, and SNe Ia Diversity | The origin of the iron-group elements titanium to zinc in nature is
understood to occur under explosive burning conditions in both Type Ia
(thermonuclear) and Type II (core collapse) supernovae. In these dynamic
environments, the most abundant product is found to be 56Ni ({\tau} = 8.5 days)
that decays through 56Co ({\... | 1107.1278v1 |
2011-07-07 | Synthesis, crystal structure and magnetism of beta-Fe1.00(2)Se1.00(3) single crystals | Understanding iron based superconductors requires high quality impurity free
single crystals. So far they have been elusive for beta-FeSe and extraction of
intrinsic materials properties has been compromised by several magnetic
impurity phases. Herein we report synchrotron - clean beta-FeSe superconducting
single cryst... | 1107.1496v1 |
2011-07-09 | Pairing mechanism in multiband superconductors | We investigate pairing mechanism in multiband superconductors. To put our
feet on firm ground, unbiased renormalization group analysis is carried out for
iron-based superconductors. It is quite remarkable that, after integrating out
quantum fluctuations, the renormalization-group flows agree exceedingly well
with a mea... | 1107.1796v2 |
2011-07-11 | Fermi-surface reconstruction involving two Van Hove singularities across the antiferromagnetic transition in BaFe2As2 | We report an angle-resolved photoemission study of BaFe2As2, a parent
compound of iron-based superconductors. Low-energy tunable excitation photons
have allowed the first observation of a saddle-point singularity at the Z
point, as well as the Gamma point. With antiferromagnetic ordering, both of
these two van Hove sin... | 1107.1960v2 |
2011-07-11 | The need for a local source of UHE CR nuclei | Recent results of the Pierre Auger (Auger) fluorescence detectors indicate an
increasingly heavy composition of ultra-high energy (UHE) cosmic rays (CRs).
Assuming that this trend continues up to the highest energies observed by the
Auger surface detectors we derive the constraints this places on the local
source distr... | 1107.2055v2 |
2011-07-11 | New Indivisible Geoscience Paradigm | Earth's interior, I posit, is like one of the rare, oxygen-starved "enstatite
chondrite" meteorites (and unlike a more-oxidized "ordinary chondrite" as has
been believed for seventy years). Laboratory-analyzed enstatite-chondrite
samples are comparable to having-in-hand impossibleto- gather deep-Earth
samples. Enstatit... | 1107.2149v1 |
2011-07-13 | The MOLDY short-range molecular dynamics package | We describe a parallelised version of the MOLDY molecular dynamics program.
This Fortran code is aimed at systems which may be described by short-range
potentials and specifically those which may be addressed with the embedded atom
method. This includes a wide range of transition metals and alloys. MOLDY
provides a ran... | 1107.2619v1 |
2011-07-14 | Successive transition from superconducting to antiferromagnetic phase in (Ca_6(Al, Ti)_4O_y)Fe_2As_2 studied via ^{75}As and ^{27}Al NMR | An unusual successive phase transition from superconducting (SC) to
antiferromagnetic (AF) phases was discovered via ^{75}As and ^{27}Al nuclear
magnetic resonance (NMR) in (Fe_2As_2)(Ca_6(Al, Ti)_4O_y) with four (Al, Ti)O
layers intercalated between FeAs planes. Although the spatially-uniform AF
ordering is clearly vi... | 1107.2765v2 |
2011-07-15 | Satellites and large doping- and temperature-dependence of electronic properties in hole-doped BaFe2As2 | Over the last years, superconductivity has been discovered in several
families of iron-based compounds. Despite intense research, even basic
electronic properties of these materials, such as Fermi surfaces, effective
electron masses, or orbital characters are still subject to debate. Here, we
address an issue that has ... | 1107.3128v1 |
2011-07-21 | A de Haas-van Alphen study of the Fermi surfaces of superconducting LiFeP and LiFeAs | We report a de Haas-van Alphen (dHvA) oscillation study of the 111 iron
pnictide superconductors LiFeAs with T_c ~18K and LiFeP with T_c~5K. We find
that for both compounds the Fermi surface topology is in good agreement with
density functional band-structure calculations and shows quasi-nested electron
and hole bands.... | 1107.4375v2 |
2011-07-22 | The Chemical and Dynamical Evolution of Isolated Dwarf Galaxies | Using a suite of simulations (Governato et al. 2010) which successfully
produce bulgeless (dwarf) disk galaxies, we provide an analysis of their
associated cold interstellar media (ISM) and stellar chemical abundance
patterns. A preliminary comparison with observations is undertaken, in order to
assess whether the prop... | 1107.4538v1 |
2011-07-25 | Uncertainties in modeling low-energy neutrino induced reactions on iron group nuclei | Charged-current neutrino-nucleus cross sections for 54,56Fe and 58,60Ni are
calculated and compared using frameworks based on relativistic and Skyrme
energy density functionals, and the shell model. The current theoretical
uncertainties in modeling neutrino-nucleus cross sections are assessed in
relation to the predict... | 1107.4872v2 |
2011-08-01 | Propagation of Ultrahigh Energy Nuclei in the Magnetic Field of our Galaxy | In this work, we present detailed simulations for propagation of ultra-high
energy (UHE) heavy nuclei, with E > 60 EeV, within recent Galactic Magnetic
Field (GMF) models. We investigate the impacts of the regular and turbulent
components of the GMF. We show that with UHE heavy nuclei, there is no
one-to-one correspond... | 1108.0362v2 |
2011-08-01 | Critical fields, thermally-activated transport and critical current density of beta-FeSe single crystals | We present critical fields, thermally-activated flux flow (TAFF) and critical
current density of tetragonal phase beta-FeSe single crystals. The upper
critical fields Hc2(T) for H||(101) and H\bot(101) are nearly isotropic and are
likely governed by Pauli limiting process. The obtained large Ginzburg-Landau
parameter k... | 1108.0407v1 |
2011-08-02 | Spin fluctuations and unconventional pairing in KFe$_2$As$_2$ | We study the relation between the spin fluctuation and superconductivity in
an heavily hole doped end material KFe$_2$As$_2$. We construct a five orbital
model by approximately unfolding the Brillouin zone of the three dimensional
ten orbital model obtained from first principles calculation. By applying the
random phas... | 1108.0657v2 |
2011-08-02 | What controls the phase diagram and superconductivity in Ru substituted BaFe$_2$As$_2$? | We use high resolution angle-resolved photoemission to study the electronic
structure of the iron based high-temperature superconductors
Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ as a function of Ru concentration. We find that
substitution of Ru for Fe is isoelectronic, i. e., it does not change the value
of the chemical potentia... | 1108.0711v2 |
2011-08-03 | Planar hybrid superconductor-normal metal-superconductor thin film junctions based on BaFe1.8Co0.2As2 | To investigate the transport properties of iron based superconductors, we
prepared planar hybrid superconductor-normal metal-superconductor (SNS') thin
film junctions with BaFe1.8Co0.2As2 as base electrode. As counter electrode we
used a lead indium alloy, while the normal metal layer was formed by thin gold
films. Tem... | 1108.0851v2 |
2011-08-04 | $β$-decay of key titanium isotopes in stellar environment | Amongst iron regime nuclei, $\beta$-decay rates on titanium isotopes are
considered to be important during the late phases of evolution of massive
stars. The key $\beta$-decay isotopes during presupernova evolution were
searched from available literature and a microscopic calculation of the decay
rates were performed u... | 1108.1026v1 |
2011-08-08 | Conceptual design of 20 T dipoles for high-energy LHC | Availability of 20 T operational field dipole magnets would open the way for
a 16.5 TeV beam energy accelerator in the LHC tunnel. Here we discuss the main
issues related to the magnet design of this extremely challenging dipole: main
constraints, superconductor choice, coil lay-out, iron, forces and stresses,
and fiel... | 1108.1619v1 |
2011-08-08 | Synthesis, crystal and magnetic structure of iron selenide BaFe2Se3 with possible superconductivity at Tc=11K | We report on synthesis of single crystals of BaFe2Se3 and study of their
crystal and magnetic structures by means of synchrotron single crystal X-ray
and neutron powder diffraction. The crystal structure has orthorhombic symmetry
and consists of double chains of FeSe4 edge connected tetrahedra intercalated
by barium. B... | 1108.1670v3 |
2011-08-11 | Chemical abundances and kinematics of a sample of metal-rich barium stars | We determined the atmospheric parameters and abundance pattern for a sample
of metal-rich barium stars. We used high-resolution optical spectroscopy.
Atmospheric parameters and abundances were determined using the local
thermodynamic equilibrium atmosphere models of Kurucz and the spectral analysis
code MOOG. We show t... | 1108.2500v1 |
2011-08-12 | Nuclear medium effects in $ν/\barν$-A DIS | Nuclear medium effects in the weak structure functions $F_2(x,Q^2)$ and
$F_3(x,Q^2)$ have been studied for deep inelastic neutrino/antineutrino
reactions in iron nucleus by taking into account Fermi motion, binding, pion
and rho meson cloud contributions, target mass correction, shadowing and
anti-shadowing corrections... | 1108.2564v1 |
2011-08-17 | A minimum single-band model for low-energy excitations in superconducting K$_x$Fe$_2$Se$_2$ | We propose a minimum single-band model for the newly discovered iron-based
superconducting K$_x$Fe$_2$Se$_2$. Our model is found to be numerically
consistent with the five-orbital model at low energies. Based on our model and
the random phase approximation, we study the spin fluctuation and the pairing
symmetry of supe... | 1108.3491v1 |
2011-08-17 | Proximity fingerprint of s+- superconductivity | We suggest a straightforward and unambiguous test to identify possible
opposite signs of superconducting order parameter in different bands proposed
for iron-based superconductors (s+- state). We consider proximity effect in a
weakly coupled sandwich composed of a s+- superconductor and thin layer of
s-wave superconduc... | 1108.3515v3 |
2011-08-22 | Block Spin Magnetic Phase Transition of A$_y$Fe$_{1.6}$Se$_2$ Under High Pressure | We predict an unconventional magnetic ground state in A$_y$Fe$_{1.6}$Se$_2$
with $\sqrt{5}\times\sqrt{5}$ Fe-vacancy superstructure under hydraulic
external pressure based on first-principles simulations. While the Fe-vacancy
ordering persists up to at least $\sim $ 12GPa, the magnetic ground state goes
at $\sim$10GPa ... | 1108.4322v2 |
2011-08-23 | Unconventional multiband superconductivity with nodes in single-crystalline SrFe2(As_0.65P_0.35)2 as seen via 31P-NMR and specific heat | We report 31P-NMR and specific heat measurements on an iron (Fe)-based
superconductor SrFe2(As0.65P0.35)2 with Tc=26 K, which have revealed the
development of antiferromagnetic correlations in the normal state and the
unconventional superconductivity(SC) with nodal gap dominated by the gapless
low-lying quasiparticle e... | 1108.4480v2 |
2011-08-24 | In vitro toxicity and uptake of magnetic nanorods | In this paper we investigate the internalization and cytotoxicity of
nanostructured materials having the form of elongated rods, with diameter of
200 nm and lengths 1 - 10 {\mu}m. The rods were made from the controlled
aggregation of sub-10 nm iron oxide nanoparticles. Recently, we have shown that
the nanorods inherite... | 1108.4773v1 |
2011-08-25 | XHIP: An Extended Hipparcos Compilation | We present the Extended Hipparcos Compilation (XHIP), a database of all stars
in the New Reduction of the Hipparcos Catalog extensively cross-referenced with
data from a broad survey of presently available sources. The resulting
collection uniquely assigns 116,096 spectral classifications, 46,392 radial
velocities, and... | 1108.4971v2 |
2011-08-30 | X-ray evidence for the accretion disc-outflow connection in 3C 111 | We present the spectral analysis of three Suzaku XIS observations of 3C 111
requested to monitor the predicted variability of its ultra-fast outflow on ~7
days time-scales. We detect an ionized iron emission line in the first
observation and a blue-shifted absorption line in the second, when the flux is
~30% higher. Th... | 1108.6095v1 |
2011-09-07 | Probing the Order Parameter of Superconducting LiFeAs using Pb/LiFeAs and Au/LiFeAs Point-Contact Spectroscopy | We have fabricated c-axis point contact junctions between high-quality LiFeAs
single crystals and Pb or Au tips in order to study the nature of the
superconducting order parameter of LiFeAs, one of the few stoichiometric
iron-based superconductors. The observation of the Josephson current in c-axis
junctions with a con... | 1109.1537v2 |
2011-09-09 | Microscopically derived Ginzburg-Landau theory for magnetic order in the iron pnictides | We examine the competition of the observed stripe spin density wave (SDW)
with other commensurate and incommensurate SDW phases in a two-band model of
the pnictides. Starting from this microscopic model, we rigorously derive an
expansion of the free energy in terms of the different order parameters at the
mean-field le... | 1109.2071v2 |
2011-09-09 | Competing superconducting, magnetic and charge orderings in the AF Heisenberg-Kondo lattice with Dirac electrons | Many recently discovered advanced materials, such as high-Tc cuprates, iron
pnictides and several heavy-fermions, exhibit a rich phase diagram suggesting
the presence of different competing interactions that would lead to various
types of ordering. Nevertheless, there is not yet a clear unifying picture
allowing the un... | 1109.2151v1 |
2011-09-12 | Central stars of planetary nebulae: The white dwarf connection | This paper is focused on the transition phase between central stars and white
dwarfs, i.e. objects in the effective temperature range 100,000 - 200,000 K. We
confine our review to hydrogen-deficient stars because the common H-rich
objects are subject of the paper by Ziegler et al. in these proceedings. We
address the c... | 1109.2391v1 |
2011-09-12 | Spatial and Temporal Variations of the Diffuse Iron 6.4 keV Line in the Galactic Center Region | We analyze the diffuse Fe I K-alpha line generated in the diffuse
interstellar molecular hydrogen by primary photons or subrelativistic protons
injected by Sagittarius (Sgr) A*. We showed that unlike emission from compact
molecular clouds, this emission can be permanently observed in the directions
of the Galactic cent... | 1109.2614v1 |
2011-09-14 | Long- to short-range magnetic order in fluorine-doped CeFeAsO | The evolution of the antiferromagnetic order parameter in CeFeAsO_{1-x}F_{x}
as a function of the fluorine content x was investigated primarily via
zero-field muon-spin spectroscopy. The long-range magnetic order observed in
the undoped compound gradually turns into a short-range order at x=0.04,
seemingly accompanied/... | 1109.3170v1 |
2011-09-19 | Mechanism of Cooper-pairing in layered high temperature superconductors | In this study, the pairing mechanism for layered HTS materials based on
attraction between electrons from adjacent layers is proposed. Initially, each
layer has expanded Fermi sphere owing to ridged geometry. When the two layers
are close enough for tunneling, it becomes energetically advantageous to form
correlated qu... | 1109.3978v1 |
2011-09-19 | Magnetic nanocomposites: new methodology for micromagnetic modeling and SANS experiments | A new methodology for micromagnetic simulations of magnetic nanocomposites is
presented. The methodology is especially suitable for simulations of two-phase
composites consisting of magnetically hard inclusions in a soft magnetic matrix
phase. The proposed technique allows to avoid the unnecessary discretization of
the... | 1109.4075v1 |
2011-09-20 | Fundamental Parameters and Chemical Composition of Arcturus | We derive a self-consistent set of atmospheric parameters and abundances of
17 elements for the red giant star Arcturus: Teff = 4286+/-30 K, logg =
1.66+/-0.05, and [Fe/H] = -0.52+/-0.04. The effective temperature was
determined using model atmosphere fits to the observed spectral energy
distribution from the blue to t... | 1109.4425v1 |
2011-09-21 | RKKY interaction in SDW phase of iron-based superconductors | Using the multiband model we analyze the Ruderman-Kittel-Kasuya-Yosida (RKKY)
interaction between the magnetic impurities in layered ferropnictide
superconductors. In the normal state the interaction is spin isotropic and is
dominated by the nesting features of the electron and hole bands separated by
the antiferromagn... | 1109.4643v1 |
2011-09-23 | Friedel-like Oscillations from Interstitial Iron in Superconducting Fe1+yTe0.62Se0.38 | Using polarized and unpolarized neutron scattering we show that interstitial
Fe in superconducting Fe_{1+y}Te_{1-x}Se_x induces a magnetic Friedel-like
oscillation that diffracts at Q_(in-plane)=(1/2,0) and involves >50 neighboring
Fe sites. The interstitial >2 mu_B moment is surrounded by compensating
ferromagnetic fo... | 1109.5196v1 |
2011-10-06 | Energy and Xmax reconstruction of hadron-initiated showers in surface arrays | The current methods to determine the primary energy in surface arrays are
different when dealing with hadron or photon initiated showers. In this work,
we adapt a method previously developed for photon-initiated showers to hadron
primaries. We determine the Monte Carlo parametrizations that relate the
surface energy es... | 1110.1179v1 |
2011-10-07 | Direct observation of the influence of the FeAs4 tetrahedron on superconductivity and antiferromagnetic correlations in Sr2VO3FeAs | We measure the pressure dependence of the electrical resistivity and the
crystal structure of iron superconductor Sr2VO3FeAs. Below ~10 GPa the
structure compresses but remains undeformed, with regular FeAs4 tetrahedrons,
and a constant Tc. Beyond 10GPa, the tetrahedron strongly distorts, while Tc
goes gradually to zer... | 1110.1559v1 |
2011-10-11 | Spin Glass and Semiconducting Behavior in 1D BaFe2-δSe3 Crystals | We investigate the physical properties and electronic structure of
BaFe2-{\delta}Se3 crystals, which were grown out of tellurium flux. The crystal
structure of the compound, an iron-deficient derivative of the ThCr2Si2-type,
is built upon edge-shared FeSe4 tetrahedra fused into double chains. The
semiconducting BaFe2-{... | 1110.2439v1 |
2011-10-17 | MINERvA Status and Event Reconstruction | MINERvA (Main INjector ExpeRiment v-A) is a few-GeV neutrino scattering
experiment that began taking data in the NuMI beam at Fermilab (FNAL) in the
Fall of 2009. MINERvA employs a fine-grained detector, with an eight ton active
target region composed of plastic scintillator. It also uses nuclear targets
composed of ca... | 1110.3727v1 |
2011-10-21 | Magnetic properties of spin diluted iron pnictides from muSR and NMR in LaFe1-xRuxAsO | The effect of isoelectronic substitutions on the microscopic properties of
LaFe1-xRuxAsO, for 0< x< 0.8, has been investigated by means of muSR and 139La
NMR. It was found that Ru substitution causes a progressive reduction of the
N\`eel temperature (T_N) and of the magnetic order parameter without leading to
the onset... | 1110.4812v1 |
2011-10-25 | Optical conductivity of superconducting K{0.8}Fe{2-y}Se2 single crystals: Evidence for a Josephson-coupled phase | The optical properties of the iron-chalcogenide superconductor
K{0.8}Fe{2-y}Se2, with a critical temperature Tc = 31 K, have been measured
over a wide frequency range in the a-b planes above and below Tc. The
conductivity is incoherent at room temperature, but becomes coherent
(Drude-like) at T ~ Tc; however, R_\Box ~ ... | 1110.5529v2 |
2011-10-25 | Ba{1-x}KxMn2As2: An Antiferromagnetic Local-Moment Metal | The compound BaMn2As2 with the tetragonal ThCr2Si2 structure is a
local-moment antiferromagnetic insulator with a Neel temperature TN = 625 K and
a large ordered moment mu = 3.9 mu_B/Mn. We demonstrate that this compound can
be driven metallic by partial substitution of Ba by K, while retaining the same
crystal and ant... | 1110.5546v2 |
2011-10-26 | Correlation-enhanced electron-phonon coupling: Applications of GW and screened hybrid functional to bismuthates, chloronitrides, and other high Tc superconductors | We show that the electron-phonon coupling (EPC) in many materials can be
significantly underestimated by the standard density functional theory (DFT) in
the local density approximation (LDA) due to large non-local correlation
effects. We present a simple yet efficient methodology to evaluate the
realistic EPC going bey... | 1110.5751v2 |
2011-10-26 | High transport critical current densities in textured Fe-sheathed Sr1-xKxFe2As2+Sn superconducting tapes | We report the realization of grain alignment in Sn-added Sr1-xKxFe2As2
superconducting tapes prepared by ex-situ powder-in-tube method. At 4.2 K, high
transport critical current densities Jc of 2.5x10^4 A/cm^2 (Ic = 180 A) in
self-field and 3.5x10^3 A/cm^2 (Ic = 25.5 A) in 10 T have been measured. These
values are the ... | 1110.5784v2 |
2011-11-03 | Effect of tensile stress on the in-plane resistivity anisotropy in BaFe2As2 | The effect of uniaxial tensile stress and the resultant strain on the
structural/magnetic transition in the parent compound of the iron arsenide
superconductor, BaFe$_2$As$_2$, is characterized by temperature-dependent
electrical resistivity, x-ray diffraction and quantitative polarized light
imaging. We show that stra... | 1111.0997v1 |
2011-11-03 | Doping - dependent superconducting gap anisotropy in the two-dimensional 10-3-8 pnictide Ca$_{10}$(Pt$_3$As$_8$)[(Fe$_{1-x}$Pt$_{x}$)$_2$As$_2$]$_5$ | The characteristic features of
Ca$_{10}$(Pt$_3$As$_8$)[(Fe$_{1-x}$Pt$_x$)$_2$As$_2$]$_5$ ("10-3-8")
superconductor are relatively high anisotropy and a clear separation of
superconductivity and structural/magnetic transitions, which allows studying
the superconducting gap without complications due to the coexisting ord... | 1111.1003v1 |
2011-11-07 | Effects of correlation in LiFeAs | We discuss the role of electronic correlations in the iron-based
superconductor LiFeAs by studying the effects on band structure, mass
enhancements, and Fermi surface in the framework of density functional theory
combined with dynamical mean field theory calculations. We conclude that LiFeAs
shows characteristics of a ... | 1111.1620v2 |
2011-11-08 | Superconducting proximity effect to the block antiferromagnetism in K$_{y}$Fe$_{2-x}$Se$_{2}$ | Recent discovery of superconducting (SC) ternary iron selenides has block
antiferromagentic (AFM) long range order. Many experiments show possible
mesoscopic phase separation of the superconductivity and antiferromagnetism,
while the neutron experiment reveals a sizable suppression of magnetic moment
due to the superco... | 1111.1860v1 |
2011-11-08 | A Bayesian approach to magnetic moment determination using muSR | A significant challenge in zero-field muSR experiments arises from the
uncertainty in the muon site. It is possible to calculate the dipole field (and
hence precession frequency nu) at any particular site given the magnetic moment
mu and magnetic structure. One can also evaluate f(nu), the probability
distribution func... | 1111.1980v1 |
2011-11-09 | Effect of uniaxial strain on the structural and magnetic phase transitions in BaFe$_2$As$_2$ | We report neutron scattering experiments probing the influence of uniaxial
strain on both the magnetic and structural order parameters in the parent iron
pnictide compound, BaFe$_2$As$_2$. Our data show that modest strain fields
along the in-plane orthorhombic b-axis can affect significant changes in phase
behavior sim... | 1111.2326v2 |
2011-11-14 | VLT/X-shooter observations and the chemical composition of cool white dwarfs | We present a model atmosphere analysis of cool hydrogen-rich white dwarfs
observed at the Very Large Telescope (VLT) with the X-shooter spectrograph. The
intermediate-dispersion and high signal-to-noise ratio of the spectra allowed
us to conduct a detailed analysis of hydrogen and heavy element line profiles.
In partic... | 1111.3250v1 |
2011-11-14 | Quantised orbital angular momentum transfer and magnetic dichroism in the interaction of electron vortices with matter | Following the very recent experimental realisation of electron vortices, we
consider their interaction with matter, in particular the transfer of orbital
angular momentum in the context of electron energy loss spectroscopy, and the
recently observed dichroism in thin film magnetised iron samples. We show here
that orbi... | 1111.3259v2 |
2011-11-15 | Unconventional Anisotropic s-Wave Superconducting Gaps of LiFeAs Iron-Pnictide Superconductor | We have performed high-resolution angle-resolved photoemission spectroscopy
on Fe-based superconductor LiFeAs (Tc = 18 K). We reveal multiple nodeless
superconducting (SC) gaps with 2D/kBTc ratios varying from 2.8 to 6.4,
depending on the Fermi surface (FS). We also succeeded in directly observing a
gap anisotropy alon... | 1111.3496v2 |
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