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2010-01-19 | High-Resolution Spectroscopy of Extremely Metal-Poor Stars in the Least Evolved Galaxies: Leo IV | We present high-resolution Magellan/MIKE spectroscopy of the brightest star
in the ultra-faint dwarf galaxy Leo IV. We measure an iron abundance of [Fe/H]
= -3.2, adding to the rapidly growing sample of extremely metal-poor stars
being identified in Milky Way satellite galaxies. The star is enhanced in the
alpha elemen... | 1001.3137v2 |
2010-02-16 | Electron-doping evolution of the low-energy spin excitations in the iron arsenide BaFe$_{2-x}$Ni$_{x}$As$_{2}$ superconductors | We use elastic and inelastic neutron scattering to systematically investigate
the evolution of the low-energy spin excitations of the iron arsenide
superconductor BaFe2-xNixAs2 as a function of nickel doping x. In the undoped
state, BaFe2As2 exhibits a tetragonal-to-orthorhombic structural phase
transition and simultan... | 1002.3133v2 |
2010-04-07 | Iron oxide doped boron nitride nanotubes: structural and magnetic properties | A first-principles formalism is employed to investigate the interaction of
iron oxide (FeO) with a boron nitride (BN) nanotube. The stable structure of
the FeO-nanotube has Fe atoms binding N atoms, with bond length of roughly
$\sim$2.1 \AA, and binding between O and B atoms, with bond length of 1.55 \AA.
In case of sm... | 1004.1151v2 |
2010-04-20 | Terzan 5: an alternative interpretation for the split horizontal branch | We consider the horizontal branch (HB) of the Globular Cluster Terzan 5,
recently shown to be split into two parts, the fainter one (delta M_K ~ 0.3mag)
having a lower metallicity than the more luminous. Both features show that it
contains at least two stellar populations. The separation in magnitude has been
ascribed ... | 1004.3426v1 |
2010-04-26 | A strong and broad iron line in the XMM-Newton spectrum of the new X-ray transient and black-hole candidate XTE J1652-453 | We observed the new X-ray transient and black-hole candidate XTE J1652-453
simultaneously with XMM-Newton and the Rossi X-ray Timing Explorer (RXTE). The
observation was done during the decay of the 2009 outburst, when XTE J1652-453
was in the hard-intermediate state. The spectrum shows a strong and broad iron
emission... | 1004.4442v2 |
2010-04-28 | Are C-rich ultra iron poor stars also He-rich? | (abridged) The three most iron poor stars presently known ([Fe/H] equal to
-5.96, -5.4 and -4.75) are carbon-rich, they are called C-Rich Ultra-Metal Poor
Stars (CRUMPS). The origin of their peculiar surface abundances is not
understood. We propose a synthetic view of the different models so far proposed
to explain the... | 1004.5024v1 |
2010-05-08 | Non-Resonant X-ray Magnetic Scattering on Rare-Earth Iron Borates RFe$_3$(BO$_3$)$_4$ | Hard x-ray scattering (HXS) experiments with a photon energy of 100keV were
performed as a function of temperature and applied magnetic field on selected
compounds of the RFe$_3$(BO$_3$)$_4$ family. The results show the presence of
several unexpected diffraction features, in particular non-resonant magnetic
reflections... | 1005.1333v2 |
2010-05-13 | Vacancy ordering and electronic structure of gamma-Fe2O3 (maghemite): a theoretical investigation | The crystal structure of the iron oxide gamma-Fe2O3 is usually reported in
either the cubic system (space group P4332) with partial Fe vacancy disorder or
in the tetragonal system (space group P41212) with full site ordering and
c/a\approx 3. Using a supercell of the cubic structure, we obtain the spectrum
of energies ... | 1005.2370v1 |
2010-05-13 | Competing order and nature of the pairing state in the iron pnictides | We show that the competition between magnetism and superconductivity can be
used to determine the pairing state in the iron arsenides. To this end we
demonstrate that the itinerant antiferromagnetic phase (AFM) and the
unconventional $s^{+-}$ sign-changing superconducting state (SC) are near the
borderline of microscop... | 1005.2437v3 |
2010-05-18 | Spectral variability of the peculiar A-type supergiant 3Pup | Optical spectra of the peculiar supergiant 3Pup taken in 1997-2008 are used
to analyze the spectral peculiarities and velocity field in its atmosphere. The
profiles of strong FeII lines and of the lines of other iron-group ions have a
specific shape: the wings are raised by emissions, whereas the core is
sharpened by a... | 1005.3098v1 |
2010-05-18 | A New Limit on the Distances of Nuclei UHECRs Sources | Recent evidence from the Pierre Auger Observatory suggests a transition, at 5
EeV-10EeV in the composition of Ultra High Energy Cosmic Rays (UHECRs), from
protons to heavier nuclei such as iron. I consider here the implications of the
heavier composition on the sources of UHECRs. The smaller magnetic rigidity
implies t... | 1005.3311v1 |
2010-05-19 | Thermodynamic Limits on Magnetodynamos in Rocky Exoplanets | To ascertain whether magnetic dynamos operate in rocky exoplanets more
massive or hotter than the Earth, we developed a parametric model of a
differentiated rocky planet and its thermal evolution. Our model reproduces the
established properties of Earth's interior and magnetic field at the present
time. When applied to... | 1005.3523v1 |
2010-05-21 | Observation of Lattice and Andreev Bound States of Vortices in Ba0.6K0.4Fe2As2 Single Crystals with Scanning Tunneling Microscopy/Spectroscopy | For a type-II superconductor, when the applied magnetic field is higher than
the lower critical value Hc1, the magnetic flux will penetrate into the
superconductor and form quantized vortices, which usually are arranged in an
Abrikosov lattice. For the newly discovered iron pnictide superconductors,
previous measuremen... | 1005.4038v1 |
2010-05-25 | The pairing state in KFe2As2 studied by measurements of the magnetic vortex lattice | Understanding the mechanism and symmetry of electron pairing in iron-based
superconductors represents an important challenge in condensed matter physics
[1-3]. The observation of magnetic flux lines - "vortices" - in a
superconductor can contribute to this issue, because the spatial variation of
magnetic field reflects... | 1005.4468v2 |
2010-06-11 | Scaling of normal-state transport properties of 1111 iron-pnictide superconductors | We show that the zero field normal-state resistivity above Tc for various
levels of electron doping-both for underdoped, optimally, and overdoped
LaO1-xFxFeAs, i.e. (x=0.05-0.075 and 0.1-0.2) and underdoped SmO1-xFxFeAs
(x=0.06- 0.1) members of the 1111-iron-pnictide superconductor family-can be
scaled in a broad tempe... | 1006.2350v2 |
2010-07-12 | Magnetic order in orbital models of the iron pnictides | We examine the appearance of the experimentally-observed stripe
spin-density-wave magnetic order in five different orbital models of the iron
pnictide parent compounds. A restricted mean-field ansatz is used to determine
the magnetic phase diagram of each model. Using the random phase approximation,
we then check this ... | 1007.1949v2 |
2010-07-15 | Spectroscopic survey of M--type asteroids | M-type asteroids, as defined in the Tholen taxonomy (Tholen, 1984), are
medium albedo bodies supposed to have a metallic composition and to be the
progenitors both of differentiated iron-nickel meteorites and enstatite
chondrites. We carried out a spectroscopic survey in the visible and near
infrared wavelength range (... | 1007.2582v1 |
2010-07-16 | High-Resolution X-ray Spectroscopy of the Interstellar Medium | The interstellar medium (ISM) has a multiphase structure characterized by
gas, dust and molecules. The gas can be found in different charge states:
neutral, low-ionized (warm) and high-ionized (hot). It is possible to probe the
multiphase ISM through the observation of its absorption lines and edges in the
X-ray spectr... | 1007.2796v1 |
2010-07-16 | Crystal Symmetry and Magnetic Order in Iron Pnictides: a Tight Binding Wannier Function Analysis | To perform a local orbital analysis of electronic and magnetic interactions,
we construct the Wannier functions (WFs) of the Fe $3d$ orbitals in the parent
compound of the recently discovered iron pnictide superconductors, LaFeAsO, and
a comparison material LaFePO. Comparing the WFs for the stripe
antiferromagnetic ord... | 1007.2878v1 |
2010-07-21 | Pseudogap of Superconducting correlation origin in iron-pnictide superconductor Ba0.6+δK0.4-δFe2As2 | Pseudogap (PG), a phenomenon of opening of gap like features above
superconducting (SC) transition temperature (Tc), has been universally observed
in the high-Tc cuprates (HTC) (1,2), some heavy fermion superconductors (3),
and iron pnictides (4-7). Here, we report the observation of PG behavior in
optical conductivity... | 1007.3617v1 |
2010-07-29 | Dissimilarities between the electronic structure of chemically doped and chemically pressurized iron pnictides from an angle-resolved photoemission spectroscopy study | We have studied the electronic structure of EuFe2As2-xPx using high
resolution angle-resolved photoemission spectroscopy. Upon substituting As with
the isovalent P, which leads to a chemical pressure and to superconductivity,
we observe a non-rigid-band like change of the electronic structure along the
center of the Br... | 1007.5205v1 |
2010-07-29 | Spectral analysis for the iron-based superconductors: Anisotropic spin fluctuations and fully gapped s^{\pm}-wave superconductivity | Spin fluctuations are considered to be one of the candidates that drive a
sign-reversed s^{\pm} superconducting state in the iron pnictides. In the
magnetic scenario, whether the spin fluctuation spectrum exhibits certain
unique fine structures is an interesting aspect for theoretical study in order
to understand exper... | 1007.5321v3 |
2010-09-22 | 3D MHD simulations of subsurface convection in OB stars | During their main sequence evolution, massive stars can develop convective
regions very close to their surface. These regions are caused by an opacity
peak associated with iron ionization. Cantiello et al. (2009) found a possible
connection between the presence of sub-photospheric convective motions and
small scale sto... | 1009.4462v1 |
2010-10-05 | Renormalization group flow, competing phases, and the structure of superconducting gap in multi-band models of Iron based superconductors | We perform an analytical renormalization group (RG) study to address the role
of Coulomb repulsion, the competition between extended s-wave superconducting
order (s+-) and the spin-density wave (SDW) order and the angular dependence of
the superconducting gap in multi-pocket models of Iron based superconductors.
Previo... | 1010.0984v3 |
2010-10-08 | Parity-odd multipoles, magnetic charges and chirality in haematite (alfa-Fe2O3) | Collinear and canted magnetic motifs in haematite were investigated by
Kokubun et al. (2008) using x-ray Bragg diffraction magnified at the iron
K-edge, and analyses of observations led to various potentially interesting
conclusions. We demonstrate that the reported analyses for both non-resonant
and resonant magnetic ... | 1010.1686v3 |
2010-11-02 | Electron transport and anisotropy of the upper critical magnetic field in a Ba0.68K0.32Fe2As2 single crystals | Early work on the iron-arsenide compounds supported the view, that a reduced
dimensionality might be a necessary prerequisite for high-Tc superconductivity.
Later, however, it was found that the zero-temperature upper critical magnetic
field, Hc2(0), for the 122 iron pnictides is in fact rather isotropic. Here, we
repo... | 1011.0698v1 |
2011-01-18 | Microturbulent velocity from stellar spectra: a comparison between different approaches (Research Note) | Context --- The classical method to infer microturbulent velocity in stellar
spectra requires that the abundances of the iron lines are not correlated with
the observed equivalent widths. An alternative method, requiring the use of the
expected line strength, is often used to by-pass the risk of spurious slopes
due to ... | 1101.3426v1 |
2011-01-24 | Distinct Fermi Surface Topology and Nodeless Superconducting Gap in (Tl0.58Rb0.42)Fe1.72Se2 Superconductor | High resolution angle-resolved photoemission measurements have been carried
out to study the electronic structure and superconducting gap of the
(Tl$_{0.58}$Rb$_{0.42}$)Fe$_{1.72}$Se$_2$ superconductor with a T$_c$=32 K. The
Fermi surface topology consists of two electron-like Fermi surface sheets
around $\Gamma$ point... | 1101.4556v1 |
2011-02-10 | An effective quantum parameter for strongly correlated metallic ferromagnets | The correlated motion of electrons in multi-orbital metallic ferromagnets is
investigated in terms of a realistic Hubbard model with {\cal N}-fold orbital
degeneracy and arbitrary intra- and inter-orbital Coulomb interactions U and J
using a Goldstone-mode-preserving non-perturbative scheme. An effective quantum
parame... | 1102.2115v1 |
2011-03-05 | Physics and measurements of magnetic materials | Magnetic materials, both hard and soft, are used extensively in several
components of particle accelerators. Magnetically soft iron-nickel alloys are
used as shields for the vacuum chambers of accelerator injection and extraction
septa; Fe-based material is widely employed for cores of accelerator and
experiment magnet... | 1103.1069v1 |
2011-03-22 | Dipolar Interactions between Iron-Oxide Nanoparticles in Frozen Ferrofluids and Ferronematics | We present a detailed study of the magnetic behavior of iron-oxide
(gamma-Fe2O3 and Fe3O4) nanoparticles constituents of ferrofluids (FF's) with
average particle sizes <d> = 2.5 and 10 nm. The particles were dispersed in the
frozen liquid carrier (pure FF) and in a frozen lyotropic liquid crystalline
matrix in the nema... | 1103.4403v1 |
2011-04-04 | X-ray Spectroscopy of MXB 1728-34 with XMM-Newton | We have analysed an XMM-Newton observation of the low mass X-ray binary and
atoll source MXB 1728-34. The source was in a low luminosity state during the
XMM-Newton observation, corresponding to a bolometric X-ray luminosity of
5*10E36 d^2 erg/s, where d is the distance in units of 5.1 kpc. The 1-11 keV
X-ray spectrum ... | 1104.0566v1 |
2011-04-22 | Non-LTE line formation for Fe I and Fe II in the atmospheres of A-F type stars | Non-local thermodynamical equilibrium (non-LTE) line formation for neutral
and singly-ionized iron is considered through a range of spectral types when
the effective temperature varies from 6500 K up to 8500 K, the gravity from log
g = 4 down to log g = 3, and the metallicity is solar one. The non-LTE
calculations were... | 1104.4403v1 |
2011-05-11 | Doping-induced vertical line nodes in the superconducting gap of the iron arsenide K-Ba122 from directional thermal conductivity | The thermal conductivity k of the iron-arsenide superconductor K-Ba122 was
measured down to 50 mK in a magnetic field up to 15 T, for a heat current
parallel and perpendicular to the tetragonal c axis. In the range from optimal
doping (x ~ 0.4) down to x = 0.16, there is no residual linear term in k(T) at
T = 0, showin... | 1105.2232v2 |
2011-05-21 | Specific Heat Discontinuity, deltaC, at Tc in BaFe2(As0.7P0.3)2 - Consistent with Unconventional Superconductivity | We report the specific heat discontinuity, deltaC/Tc, at Tc = 28.2 K of a
collage of single crystals of BaFe2(As0.7P0.3)2 and compare the measured value
of 38.5 mJ/molK**2 with other iron pnictide and iron chalcogenide (FePn/Ch)
superconductors. This value agrees well with the trend established by Bud'ko,
Ni and Canfie... | 1105.4289v1 |
2011-06-03 | Iron-based n-type electron-induced ferromagnetic semiconductor | Carrier-induced ferromagnetic semiconductors (FMSs) have been intensively
studied for decades as they have novel functionalities that cannot be achieved
with conventional metallic materials. These include the ability to control
magnetism by electrical gating or light irradiation, while fully inheriting the
advantages o... | 1106.0561v3 |
2011-06-06 | Correlation of conductivity and angle integrated valence band photoemission characteristics in single crystal iron perovskites for 300 K < T < 800 K: Comparison of surface and bulk sensitive methods | A single crystal monolith of La0.9Sr0.1FeO3 and thin pulsed laser deposited
film of La0.8Sr0.2Fe0.8Ni0.2O3 were subject to angle integrated valence band
photoemission spectroscopy in ultra high vacuum and conductivity experiments in
ambient air at temperatures from 300 K to 800 K. Except for several sputtering
and anne... | 1106.1034v1 |
2011-06-15 | No X-Ray Excess from the HESS J1741-302 Region except a New Intermediate Polar Candidate | With the Suzaku satellite, we observed an unidentified TeV gamma-ray source
HESS J1741$-$302 and its surroundings. No diffuse or point-like X-ray sources
are detected from the bright southern emission peak of HESS J1741$-$302. From
its neighborhood, we found a new intermediate polar candidate at the position
of $(\alph... | 1106.2861v1 |
2011-06-15 | Electronic identification of the actual parental phase of KxFe2-ySe2 superconductor and its intrinsic mesoscopic phase separation | While the parent compounds of the cuprate high temperature superconductors
(high-Tc's) are Mott insulators, the iron-pnictide high-Tc's are in the
vicinity of a metallic spin density wave (SDW) state, which highlights the
difference between these two families. However, insulating parent compounds
were identified for th... | 1106.3026v1 |
2011-06-19 | Iron Based Superconductors: Pnictides versus Chalcogenides | We present a brief review of the present day situation with studies of
high-temperature superconductivity in iron pnictides and chalcogenides. Recent
discovery of superconductivity with T_c > 30 K in A_xFe_{2-x/2}Se_2
(A=K,Cs,Tl,...) represents the major new step in the development of new
concepts in the physics of Fe ... | 1106.3707v1 |
2011-06-24 | Unprecedented anisotropic metallic state in BaFe2As2 revealed by optical spectroscopy | An ordered phase showing remarkable electronic anisotropy in proximity to the
superconducting phase is now a hot issue in the field of
high-transition-temperature superconductivity. As in the case of copper oxides,
superconductivity in iron arsenides competes or coexists with such an ordered
phase. Undoped and underdop... | 1106.4967v1 |
2011-06-27 | Silicon and Oxygen Abundances in Planet-Host Stars | The positive correlation between planet detection rate and host star iron
abundance lends strong support to the core accretion theory of planet
formation. However, iron is not the most significant mass contributor to the
cores of giant planets. Since giant planet cores are thought to grow from
silicate grains with icy ... | 1106.5509v1 |
2011-06-28 | Pressure-induced isostructural phase transition and correlation of FeAs coordination with the superconducting properties of 111-type Na1-xFeAs | The effect of pressure on the crystalline structure and superconducting
transition temperature (Tc) of the 111-type Na1-xFeAs system using in situ high
pressure synchrotron x-ray powder diffraction and diamond anvil cell techniques
is studied. A pressure-induced tetragonal to tetragonal isostructural phase
transition w... | 1106.5640v1 |
2011-06-30 | Suzaku Observation of the Intermediate Polar V1223 Sagittarii | We report on the Suzaku observation of the intermediate polar V1223
Sagittarii. Using a multi-temperature plasma emission model with its reflection
from a cold matter, we obtained the shock temperature to be 37.9^{+5.1}_{-4.6}
keV. This constrains the mass and the radius of the white dwarf (WD) in the
ranges 0.82^{+0.0... | 1106.6111v1 |
2011-08-09 | Magnetic spots on hot massive stars | Hot luminous stars show a variety of phenomena in their photospheres and
winds which still lack clear physical explanation. Among these phenomena are
photospheric turbulence, line profile variability (LPV), non-thermal emission,
non-radial pulsations, discrete absorption components (DACs) and wind clumping.
Cantiello e... | 1108.2030v1 |
2011-08-23 | Fine-Grid Calculations for Stellar Electron and Positron Capture Rates on Fe-Isotopes | The acquisition of precise and reliable nuclear data is a prerequisite to
success for stellar evolution and nucleosynthesis studies. Core-collapse
simulators find it challenging to generate an explosion from the collapse of
the core of massive stars. It is believed that a better understanding of the
microphysics of cor... | 1108.4569v1 |
2011-10-09 | Preemptive nematic order, pseudogap, and orbital order in the iron pnictides | Starting from a microscopic itinerant model, we derive and analyze the
effective low-energy model for collective magnetic excitations in the iron
pnictides. We show that the stripe magnetic order is generally preempted by an
Ising-nematic order which breaks $C_{4}$ lattice symmetry but preserves O(3)
spin-rotational sy... | 1110.1893v2 |
2011-11-08 | Two Populations of X-ray Pulsars Produced by Two Types of Supernovae | Two types of supernova are thought to produce the overwhelming majority of
neutron stars in the Universe. The first type, iron-core collapse supernovae,
occurs when a high-mass star develops a degenerate iron core that exceeds the
Chandrasekhar limit. The second type, electron-capture supernovae, is
associated with the... | 1111.2051v1 |
2011-11-22 | Microstructural magnetic phases in superconducting FeTe0.65Se0.35 | In this paper, we address a number of outstanding issues concerning the
nature and the role of magnetic inhomogenities in the iron chalcogenide system
FeTe1-xSex and their correlation with superconductivity in this system. We
report morphology of superconducting single crystals of FeTe0.65Se0.35 studied
with transmissi... | 1111.5176v2 |
2011-11-27 | Evolution of structural properties of iron oxide nano particles during temperature treatment from 250°C - 900°C: X-ray diffraction and Fe K-shell pre-edge X-ray absorption study | Iron oxide nano particles with nominal Fe2O3 stoichiometry were synthesized
by a wet, soft chemical method with the heat treatment temperatures from
250{\deg}C to 900{\deg}C in air. The variation in the structural properties of
the nano particles with the heat treatment temperature was studied by X-ray
diffraction and ... | 1111.6204v1 |
2011-11-29 | A J-band detection of the donor star in the dwarf nova OY Carinae, and an optical detection of its `iron curtain' | Purely photometric models can be used to determine the binary parameters of
eclipsing cataclysmic variables with a high degree of precision. However, the
photometric method relies on a number of assumptions, and to date there have
been very few independent checks of this method in the literature. We present
time-resolv... | 1111.6775v1 |
2011-12-08 | Influence of high permeability disks in an axisymmetric model of the Cadarache dynamo experiment | Numerical simulations of the kinematic induction equation are performed on a
model configuration of the Cadarache von-K\'arm\'an-Sodium dynamo experiment.
The effect of a localized axisymmetric distribution of relative permeability
{\mu} that represents soft iron material within the conducting fluid flow is
investigate... | 1112.1780v2 |
2011-12-20 | Spin Dynamics of a J1-J2-K Model for the Paramagnetic Phase of Iron Pnictides | We study the finite-temperature spin dynamics of the paramagnetic phase of
iron pnictides within an antiferromagnetic J_1-J_2 Heisenberg model on a square
lattice with a biquadratic coupling $-K (S_i \cdot S_j)^2$ between the
nearest-neighbor spins. Our focus is on the paramagnetic phase in the parameter
regime of this... | 1112.4785v3 |
2012-01-16 | Universal heat conduction in the iron-arsenide superconductor KFe2As2 : Evidence of a d-wave state | The thermal conductivity of the iron-arsenide superconductor KFe2As2 was
measured down to 50 mK for a heat current parallel and perpendicular to the
tetragonal c-axis. A residual linear term (RLT) at T=0 is observed for both
current directions, confirming the presence of nodes in the superconducting
gap. Our value of t... | 1201.3376v3 |
2012-01-26 | Very fast photometric and X-ray observations of the intermediate polar V2069 Cygni (RX J2123.7+4217) | We present fast timing photometric observations of the intermediate polar
V2069 Cygni (RX J2123.7+4217) using the Optical Timing Analyzer (OPTIMA) at the
1.3 m telescope of Skinakas Observatory. The optical (450-950 nm) light curve
of V2069 Cygni was measured with sub-second resolution for the first time
during July 20... | 1201.5629v1 |
2012-02-14 | Nernst effect of iron pnictide and cuprate superconductors: signatures of spin density wave and stripe order | The Nernst effect has recently proven a sensitive probe for detecting unusual
normal state properties of unconventional superconductors. In particular, it
may sensitively detect Fermi surface reconstructions which are connected to a
charge or spin density wave (SDW) ordered state, and even fluctuating forms of
such a s... | 1202.2959v1 |
2012-04-04 | A New Disintegrative Capture Theory for the Origin of the Moon | The object that resulted in the creation of the Moon started in the same
orbital path as Earth around the Sun, but at Earth's L4. This proto-Moon (PM)
was 4 times less massive than the usual Giant Impact (GI) object "Theia" and
was captured into Earth orbit. It had a 32% Iron-Nickel-Sulfur core supporting
a dynamo, whi... | 1204.0980v2 |
2012-05-02 | Negative thermal expansion and antiferromagnetism in the actinide oxypnictide NpFeAsO | A neptunium analogue of the LaFeAsO tetragonal layered compound has been
synthesized and characterized by a variety of experimental techniques. The
occurrence of long-range magnetic order below a critical temperature T_N = 57 K
is suggested by anomalies in the temperature-dependent magnetic susceptibility,
electrical r... | 1205.0438v1 |
2012-05-14 | The Central Engine Structure of 3C120: Evidence for a Retrograde Black Hole or a Refilling Accretion Disk | The broad-line radio galaxy 3C120 is a powerful source of both X-ray and
radio emission including superluminal jet outflows. We report on our reanalysis
of 160 ks of Suzaku data taken in 2006, previously examined by Kataoka et al.
(2007). Spectral fits to the XIS and HXD/PIN data over a range of 0.7-45 keV
reveal a wel... | 1205.3175v1 |
2012-05-21 | Impact of the 2 Fe unit cell on the electronic structure measured by ARPES in iron pnictides | In all iron pnictides, the positions of the ligand alternatively above and
below the Fe plane create 2 inequivalent Fe sites. This results in 10 Fe 3d
bands in the electronic structure. However, they do not all have the same
status for an ARPES experiment. There are interference effects between the 2 Fe
that modulate s... | 1205.4513v1 |
2012-05-27 | Neutron-Diffraction Measurements of an Antiferromagnetic Semiconducting Phase in the Vicinity of the High-Temperature Superconducting State of K$_x$Fe$_{2-y}$Se$_2$ | The recently discovered K-Fe-Se high temperature superconductor has caused
heated debate regarding the nature of its parent compound. Transport,
angle-resolved photoemission spectroscopy, and STM measurements have suggested
that its parent compound could be insulating, semiconducting or even metallic
[M. H. Fang, H.-D.... | 1205.5992v2 |
2012-05-30 | The silicate model and carbon rich model of CoRoT-7b, Kepler-9d and Kepler-10b | Possible bulk compositions of the super-Earth exoplanets, CoRoT-7b,
Kepler-9d, and Kepler-10b are investigated by applying a commonly used silicate
and a non-standard carbon model. Their internal structures are deduced using
the suitable equation of state of the materials. The degeneracy problems of
their compositions ... | 1205.6554v2 |
2012-06-18 | Impact of Dynamic Orbital Correlations on Magnetic Excitations in the Normal State of Iron-Based Superconductors | We show here that orbital degrees of freedom produce a distinct signature in
the magnetic excitation spectrum of iron-based superconductors above the
magnetic ordering temperature. Because $d_{xz}$ and $d_{yz}$ orbitals are
strongly connected with the Fermi surface topology, the nature of magnetic
excitations can be mo... | 1206.4095v2 |
2012-06-29 | Laser spectroscopy of finite size and covering effects in magnetite nanoparticles | The experiments on the impact of the size of magnetite clusters on various
magnetic properties (magnetic moment, Curie temperature, blocking temperature
etc.) have been carried out. The methods of magnetic separation, centrifuging
of water suspensions of biocompatible iron oxide nanoparticles (NPs) allow
producing frac... | 1206.6985v5 |
2012-07-03 | Two-dome structure in electron-doped iron arsenide superconductors | Iron arsenide superconductors based on the material LaFeAsO1-xFx are
characterized by a two-dimensional Fermi surface (FS) consisting of hole and
electron pockets yielding structural and antiferromagnetic transitions at x =
0. Electron doping by substituting O2- with F- suppresses these transitions and
gives rise to su... | 1207.0583v2 |
2012-07-13 | The nature of the multi-wavelength emission of 3C 111 | We attempt to determine the nature of the high energy emission of the radio
galaxy 3C 111, by distinguishing between the effects of the thermal and
non-thermal processes. We study the X-ray spectrum of 3C 111 between 0.4 keV
and 200 keV, and its spectral energy distribution, using data from the Suzaku
satellite combine... | 1207.3308v2 |
2012-07-16 | Searching for Massive Outflows in Holmberg IX X-1 and NGC 1313 X-1: The Iron K Band | We have analysed all the good quality XMM-Newton data publicly available for
the bright ULXs Holmberg IX X-1 and NGC 1313 X-1, with the aim of searching for
discrete emission or absorption features in the Fe K band that could provide
observational evidence for the massive outflows predicted if these sources are
accreti... | 1207.3839v1 |
2012-08-01 | Coronae above accretion disks around black holes: The effect of Compton cooling | The geometry of the accretion flow around stellar mass and supermassive black
holes depends on the accretion rate. Broad iron emission lines originating from
the irradiation of cool matter can indicate that there is an inner disk below a
hot coronal flow.These emission lines have been detected in X-ray binaries.
Observ... | 1208.0265v1 |
2012-08-18 | Gap-dependent quasiparticle dynamics and coherent acoustic phonons in parent iron pnictide CaFe2As2 across the spin density wave phase transition | We report ultrafast quasiparticle (QP) dynamics and coherent acoustic phonons
in undoped CaFe_2As_2 iron pnictide single crystals exhibiting spin-density
wave (SDW) and concurrent structural phase transition at temperature TSDW ~ 165
K using femtosecond time-resolved pump-probe spectroscopy. The contributions in
transi... | 1208.3742v2 |
2012-08-29 | Interpreting the near-infrared spectra of the 'golden standard' Type Ia supernova 2005cf | We present nine near-infrared (NIR) spectra of supernova (SN) 2005cf at
epochs from -10 d to +42 d with respect to B-band maximum, complementing the
existing excellent data sets available for this prototypical Type Ia SN at
other wavelengths. The spectra show a time evolution and spectral features
characteristic of nor... | 1208.5949v1 |
2012-09-03 | The Black Hole Spin and Soft X-ray Excess of the Luminous Seyfert Galaxy Fairall 9 | We present an analysis of all XMM-Newton and Suzaku X-ray spectra of the
nearby luminous Seyfert galaxy Fairall 9. Confirming previous analyses, we find
robust evidence for a broad iron line associated with X-ray reflection from the
innermost accretion disk. By fitting a spectral model that includes a
relativistically ... | 1209.0468v1 |
2012-09-04 | The enrichment history of the intracluster medium: a Bayesian approach | This work measures the evolution of the iron content in galaxy clusters by a
rigorous analysis of the data of 130 clusters at 0.1<z<1.3. This task is made
difficult by a) the low signal-to-noise ratio of abundance measurements and the
upper limits, b) possible selection effects, c) boundaries in the parameter
space, d)... | 1209.0565v1 |
2012-10-04 | Manipulation and detection of spin state of Iron-Porphyrin by dedicated chemisorption on magnetic substrates | One of the key factors behind the rapid evolution of molecular spintronics is
the efficient realization of spin manipulation of organic molecules with a
magnetic center. The spin state of such molecules may depend crucially on the
interaction with the substrate on which they are adsorbed. In this letter, we
demonstrate... | 1210.1376v1 |
2012-12-07 | Poly(acrylic acid)-coated iron oxide nanoparticles : quantitative evaluation of the coating properties and applications for the removal of a pollutant dye | In this work, 6 to 12 nm iron oxide nanoparticles were synthesized and coated
with poly(acrylic acid) chains of molecular weight 2100 g/mol. Based on a
quantitative evaluation of the dispersions, the bare and coated particles were
thoroughly characterized. The number densities of polymers adsorbed at the
particle surfa... | 1212.1580v1 |
2012-12-07 | Magneto-optic Faraday effect in maghemite nanoparticles/silica matrix nanocomposites prepared by the Sol-Gel method | Bulk monolithic samples of {\gamma}-Fe2O3/SiO2 composites with different iron
oxide/silica ratios have been prepared by the sol-gel technique. Iron oxide
nanoparticles are obtained in-situ during heat treatment of samples and silica
matrix consolidation. Preparation method was previously optimized to minimize
the perce... | 1212.1690v1 |
2012-12-13 | Dopant Clustering, Electronic Inhomogeneity, and Vortex Pinning in Iron-Based Superconductors | We use scanning tunneling microscopy to map the surface structure, nanoscale
electronic inhomogeneity, and vitreous vortex phase in the hole-doped
superconductor Sr$_{0.75}$K$_{0.25}$Fe$_2$As$_2$ with $T_c$=32 K. We find the
low-$T$ cleaved surface is dominated by a half-Sr/K termination with $1\times
2$ ordering and u... | 1212.3240v3 |
2013-01-07 | Persistent high-energy spin excitations in iron pnictide superconductors | Motivated by the premise that superconductivity in iron-based superconductors
is unconventional and mediated by spin fluctuations, an intense research effort
has been focused on characterizing the spin excitation spectrum in the
magnetically ordered parent phases of the Fe-pnictides2,3 and - chalcogenides4.
For these u... | 1301.1289v1 |
2013-02-21 | The Mid-Infrared and Optical Decay of SN 2011fe | We measure the decay rate of the mid-IR luminosity from type Ia supernova
2011fe between six months and one year after explosion using Spitzer/IRAC
observations. The fading in the 3.6 micron channel is 1.48+/-0.02 mag/100d,
which is similar to that seen in blue optical bands. The supernova brightness
fades at 0.78+/-0.... | 1302.5421v1 |
2013-02-24 | The X-ray Spectrum Of The Black Hole Candidate Swift J1753.5-0127 | We present a spectral analysis of the black hole candidate and X-ray
transient source Swift J1753.5 0127 making use of simultaneous observations of
XMM-Newton and Rossi X-ray Timing Explorer (RXTE) in 2006, when the source was
in outburst. The aim of this paper is to test whether a thermal component due
to the accretio... | 1302.5882v2 |
2013-03-04 | Soft lags in neutron star kHz Quasi Periodic Oscillations: evidence for reverberation? | High frequency soft reverberation lags have now been detected from stellar
mass and super massive black holes. Their interpretation involves reflection of
a hard source of photons onto an accretion disk, producing a delayed reflected
emission, with a time lag consistent with the light travel time between the
irradiatin... | 1303.0750v2 |
2013-03-07 | Abundances of neutron-capture elements in stars of the galactic disk substructures | The aim of this work is to present and discuss the observations of the iron
peak (Fe, Ni) and neutron-capture element (Y, Zr, Ba, La, Ce, Nd, Sm, and Eu)
abundances for 276 FGK dwarfs, located in the galactic disk with metallicity -1
< [Fe/H] < +0.3. Atmospheric parameters and chemical composition of the studied
stars ... | 1303.1730v1 |
2013-03-28 | New Diluted Ferromagnetic Semiconductor isostructural to 122 type iron pnictide superconductor with TC up to 180 K | Diluted magnetic semiconductors (DMS) have received much attention due to its
potential applications to spintronics devices. A prototypical system (Ga,Mn)As
has been widely studied since 1990s. The simultaneous spin and charge doping
via hetero-valence (Ga3+,Mn2+) substitution, however, resulted in severely
limited sol... | 1303.7157v1 |
2013-03-29 | Seeing the orbital ordering in Iron-based superconductors with magnetic anisotropy | The orbital fluctuation of the conduction electrons in the Iron-based
superconductors is found to contribute significantly to the magnetic response
of the system. With the use of a realistic five-band model and group
theoretical analysis, we have determined the orbital magnetic susceptibility in
such a multi-orbital sy... | 1303.7302v2 |
2013-04-01 | Carbon and Oxygen Abundances in the Hot Jupiter Exoplanet Host Star XO-2N and its Binary Companion | With the aim of connecting the compositions of stars and planets, we present
the abundances of carbon and oxygen, as well as iron and nickel, for the
transiting exoplanet host star XO-2N and its wide-separation binary companion
XO-2S. Stellar parameters are derived from high-resolution,
high-signal-to-noise spectra, an... | 1304.0395v1 |
2013-04-03 | Molybdenum, Ruthenium, and the Heavy r-process Elements in Moderately Metal-Poor Main-Sequence Turnoff Stars | The ratios of elemental abundances observed in metal-poor stars of the
Galactic halo provide a unique present-day record of the nucleosynthesis
products of its earliest stars. While the heaviest elements were synthesized by
the r- and s-processes, dominant production mechanisms of light trans-ironic
elements were obscu... | 1304.1050v1 |
2013-04-04 | Learning from Nature to Improve the Heat Generation of Iron-Oxide Nanoparticles for Magnetic Hyperthermia Applications | The performance of magnetic nanoparticles is intimately entwined with their
structure, mean size and magnetic anisotropy. Besides, ensembles offer a unique
way of engineering the magnetic response by modifying the strength of the
dipolar interactions between particles. Here we report on an experimental and
theoretical ... | 1304.1298v1 |
2013-04-18 | Hadron energy response of the Iron Calorimeter detector at the India-based Neutrino Observatory | The results of a Monte Carlo simulation study of the hadron energy response
for the magnetized Iron CALorimeter detector, ICAL, proposed to be located at
the India-based Neutrino Observatory (INO) is presented. Using a GEANT4
modeling of the detector ICAL, interactions of atmospheric neutrinos with
target nuclei are si... | 1304.5115v2 |
2013-04-19 | Understanding the re-entrant superconducting phase diagram of an iron-pnictide Ca$_4$Al$_2$O$_6$Fe$_2$(As$_{1-x}$P$_x$)$_2$ | Recently, a very rich phase diagram has been obtained for an iron-based
superconductor Ca4Al2O6Fe2(As1-xPx)2. It has been revealed that nodeless (x=0)
and nodal (x = 1) superconductivity are separated by an antiferromagnetic
phase. Here we study the origin of this peculiar phase diagram using a five
orbital model const... | 1304.5360v1 |
2013-04-24 | Deriving precise parameters for cool solar-type stars. Optimizing the iron line list | Temperature, surface gravity, and metallicitity are basic stellar atmospheric
parameters necessary to characterize a star. We aim to improve the description
of the spectroscopic temperatures especially for the cooler stars where the
differences with the Infrared Flux Method are higher, as presented in previous
work. Ou... | 1304.6639v1 |
2013-04-28 | Point Contact Spectroscopy of Fe Pnictides & Chalcogenides In The Normal State | We review the current status of point contact spectroscopy on the iron based
superconductors, focusing on their normal state. Point contact spectroscopy is
generally used to study superconductors via Andreev reflection, but in recent
years it has also proved to be a useful bulk probe of strongly correlated
electron sys... | 1304.7426v1 |
2013-05-08 | A fully quantum mechanical calculation of the diffusivity of hydrogen in iron using the tight binding approximation and path integral theory | We present calculations of free energy barriers and diffusivities as
functions of temperature for the diffusion of hydrogen in bcc-Fe. This is a
fully quantum mechanical approach since the total energy landscape is computed
using a new self consistent, transferable tight binding model for interstitial
impurities in mag... | 1305.1772v1 |
2013-05-10 | Carbon Deflagration in Type Ia Supernova: I. Centrally Ignited Models | A leading model for Type Ia supernovae (SNe Ia) begins with a white dwarf
near the Chandrasekhar mass that ignites a degenerate thermonuclear runaway
close to its center and explodes. In a series of papers, we shall explore the
consequences of ignition at several locations within such dwarfs. Here we
assume central ign... | 1305.2433v1 |
2013-05-16 | Effect of doping on the magnetostructural ordered phase of iron arsenides: A comparative study of the resistivity anisotropy in the doped BaFe$_2$As$_2$ with doping into three different sites | In order to unravel a role of doping in the iron-based superconductors, we
investigated the in-plane resistivity for BaFe$_2$As$_2$ doped at either of the
three different lattice sites, Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$,
BaFe$_2$(As$_{1-x}$P$_x$)$_2$, and Ba$_{1-x}$K$_x$Fe$_2$As$_2$, focusing on the
doping effect in the l... | 1305.3744v1 |
2013-05-31 | Supernova Ejecta in the Youngest Galactic Supernova Remnant G1.9+0.3 | G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an
estimated supernova (SN) explosion date of about 1900, and most likely located
near the Galactic Center. Only the outermost ejecta layers with free-expansion
velocities larger than about 18,000 km/s have been shocked so far in this
dynamically you... | 1305.7399v1 |
2013-05-31 | Space Velocities of Southern Globular Clusters VII. NGC 6397, NGC 6626 (M 28) and NGC 6656 (M 22) | We have measured the absolute proper motions of globular clusters NGC 6397,
NGC 6626 (M 22) and NGC 6656 (M 28) as part of our ongoing Southern
Proper-Motion Program. The reference system is the ICRS via Hipparcos stars for
these three low galactic latitude clusters. Formal errors range between ~0.3
and 0.7 mas/yr. Not... | 1305.7431v1 |
2013-06-26 | Are there missing bond paths in Trimethylenemethane-Iron-tri-carbonyl [(CO)3Fe-(C4H6)] complex? | In a recent paper [J. Organomet. Chem. (2013) doi: 10.1016 /j.jorganchem.
2013.03.047] analyzing the bonding mode of Trimethylenemethane (TMM) with some
metal carbonyls, Mousavi and Frenking have declared the absence of bond paths,
the so-called missed bond paths, between metal atoms and terminal carbon atoms
in severa... | 1306.6350v2 |
2013-07-01 | SWEET-Cat: A catalogue of parameters for Stars With ExoplanETs I. New atmospheric parameters and masses for 48 stars with planets | Due to the importance that the star-planet relation has to our understanding
of the planet formation process, the precise determination of stellar
parameters for the ever increasing number of discovered extra-solar planets is
of great relevance. Furthermore, precise stellar parameters are needed to fully
characterize t... | 1307.0354v1 |
2013-07-17 | The role of the Gamma-Eddington ratio relation on the X-ray Baldwin effect in Active Galactic Nuclei | The X-ray Baldwin effect is the inverse correlation between the equivalent
width (EW) of the narrow component of the iron Kalpha line and the X-ray
luminosity of active galactic nuclei (AGN). A similar trend has also been
observed between Fe Kalpha EW and the Eddington ratio (lambda_Edd). Using
Chandra/HEG results of S... | 1307.4507v2 |
2013-07-23 | Variable X-ray reflection from 1H~0419--577 | We present detailed broadband X-ray spectral variability of a Seyfert 1
galaxy 1H~0419--577 based on an archival \suzaku{} observation in July 2007, a
new \suzaku{} observation performed in January 2010 and the two latest \xmm{}
observations from May 2010. All the observations show soft X-ray excess
emission below $2\k... | 1307.6223v1 |
2013-08-15 | Structural and optical investigations of the iron-chalcogenide superconductor Fe$_{1.03}$Se$_{0.5}$Te$_{0.5}$ under high pressure | Iron-chalcogenide superconductor Fe$_{1.03}$Se$_{0.5}$Te$_{0.5}$ has been
investigated under high pressure using synchrotron based x-ray diffraction and
mid-infrared reflectance measurements at room temperature. Pressure dependence
of the superconducting transition temperature (T$_c$) of the same sample has
been determ... | 1308.3367v1 |
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