publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2016-04-07 | The super-super exchange mechanism in iron-based antiperovskite chalco-halides | By using the first-principles electronic structure calculations, we have
systematically studied the magnetism in three recently synthesized iron-based
antiperovskite chalco-halides: Ba$_3$(FeS$_4$)Cl, Ba$_3$(FeS$_4$)Br, and
Ba$_3$(FeSe$_4$)Br. These compounds consist of edge-sharing Ba$Q_6$ ($Q$=Cl or
Br) octahedra int... | 1604.02044v1 |
2016-04-08 | Detection of H2O and evidence for TiO/VO in an ultra hot exoplanet atmosphere | We present a primary transit observation for the ultra hot (Teq~2400K) gas
giant expolanet WASP-121b, made using the Hubble Space Telescope Wide Field
Camera 3 in spectroscopic mode across the 1.12-1.64 micron wavelength range.
The 1.4 micron water absorption band is detected at high confidence (5.4 sigma)
in the plane... | 1604.02310v1 |
2016-04-12 | A Statistical Study of the Average Iron Charge Distributions inside Magnetic Clouds for Solar Cycle 23 | Magnetic clouds (MCs) are the interplanetary counterpart of coronal magnetic
flux ropes. They can provide valuable information to reveal the flux rope
characteristics at their eruption stage in the corona, which are unable to be
explored in situ at present. In this paper, we make a comprehensive survey of
the average i... | 1604.03205v1 |
2016-04-14 | Study of Glass and Bakelite properties as electrodes in RPCs | India-based Neutrino Observatory (INO) collaboration is planning to build a
magnetized Iron-CALorimeter detector (ICAL) for the study of atmospheric
neutrinos. ICAL detector will be a stack of 151 layers of magnetized iron
plates interleaved with Resistive Plate Chambers (RPCs) as active detector
elements with a total ... | 1604.04130v2 |
2016-04-25 | Equilibrium and Sudden Events in Chemical Evolution | We present new analytic solutions for one-zone (fully mixed) chemical
evolution models and explore their implications. In contrast to existing
analytic models, we incorporate a realistic delay time distribution for Type Ia
supernovae (SNIa) and can therefore track the separate evolution of
$\alpha$-elements produced by... | 1604.07435v1 |
2016-05-01 | Development of a method for measuring blood coagulation using superparamagnetic iron oxide nanoparticles and an alternating magnetic field | We developed a method for measuring blood coagulation using superparamagnetic
iron oxide nanoparticles (SPIONs) and an alternating magnetic field (AMF). The
3rd and 5th harmonic signals from SPIONs mixed with blood induced by AMF were
detected using a gradiometer coil. Blood coagulation was induced artificially
by addi... | 1605.00255v2 |
2016-06-02 | Orbital selective spin excitations and their impact on superconductivity of LiFe1-xCoxAs | We use neutron scattering to study spin excitations in single crystals of
LiFe$_{0.88}$Co$_{0.12}$As, which is located near the boundary of the
superconducting phase of LiFe$_{1-x}$Co$_{x}$As and exhibits non-Fermi-liquid
behavior indicative of a quantum critical point. By comparing spin excitations
of LiFe$_{0.88}$Co$... | 1606.00727v1 |
2016-06-03 | Swift J174540.7-290015: a new accreting binary in the Galactic Center | We report on the identification of the new Galactic Center (GC) transient
Swift J174540.7-290015 as a likely low mass X-ray binary (LMXB) located at only
16 arcsec from Sgr A*. This transient was detected on 2016 February 6th during
the Swift GC monitoring, and it showed long-term spectral variations compatible
with a ... | 1606.01138v1 |
2016-06-17 | Time dependence of Fe/O ratio within a 3D Solar Energetic Particle propagation model including drift | Context. The intensity profiles of iron and oxygen in Solar Energetic
Particle (SEP) events often display differences that result in a decreasing
Fe/O ratio over time. The physical mechanisms behind this behaviour are not
fully understood, but these observational signatures provide important tests of
physical modelling... | 1606.05612v2 |
2016-07-05 | Heavy Electron doping-induced antiferromagnetic phase as the parent for iron-oxypnictide superconductor LaFeAsO1-xHx | We perform transport measurements and band structure calculations of
electron-doped LaFeAsO1-xHx over a wide range of x from 0.01 to 0.66. The T^2
and sqrt(T) dependency of the resistivity are observed at x ~ 0.17 and 0.41,
respectively. The sign change of RH without opening of the spin-density-wave
gap for 0.45 < x < ... | 1607.01238v1 |
2016-07-05 | Superconductivity-enhanced Nematicity and '$s+d$' Gap Symmetry in Fe(Se$_{1-x}$S$_x$) | Superconducting iron chalcogenide FeSe has the simplest crystal structure
among all the Fe-based superconductors. Unlike other iron pnictides, FeSe
exhibits no long range magnetic order accompanying the
tetragonal-to-orthorhombic structural distortion, which raises the fundamental
question about the role of magnetism a... | 1607.01288v2 |
2016-07-07 | Deciphering chemical order/disorder and material properties at the single-atom level | Correlating 3D arrangements of atoms and defects with material properties and
functionality forms the core of several scientific disciplines. Here, we
determined the 3D coordinates of 6,569 iron and 16,627 platinum atoms in a
model iron-platinum nanoparticle system to correlate 3D atomic arrangements and
chemical order... | 1607.02051v1 |
2016-07-09 | Theoretical modelling of the AGN iron-line vs continuum time-lags in the lamp-post geometry | Context: Theoretical modelling of time-lags between variations in the Fe
K$\alpha$ emission and the X-ray continuum might shed light on the physics and
geometry of the X-ray emitting region in active galaxies (AGN) and X-ray
binaries. We here present the results from a systematic analysis of time-lags
between variation... | 1607.02625v2 |
2016-07-09 | On the reality of broad iron L lines from the narrow line Seyfert 1 galaxies 1H0707-495 and IRAS 13224-3809 | We performed time resolved spectroscopy of 1H0707-495 and IRAS 13224-3809
using long XMM-Newton observations. These are strongly variable narrow line
Seyfert 1 galaxies and show broad features around 1 keV that has been
interpreted as relativistically broad Fe L$\alpha$ lines. Such features are not
clearly observed in ... | 1607.02635v1 |
2016-07-11 | Magnetotransport of multiple-band nearly-antiferromagnetic metals due to "hot-spot" scattering | Multiple-band electronic structure and proximity to antiferromagnetic (AF)
instability are the key properties of iron-based superconductors. We explore
the influence of scattering by the AF spin fluctuations on transport of
multiple-band metals above the magnetic transition. A salient feature of
scattering on the AF fl... | 1607.03194v2 |
2016-07-19 | Sensitivity of the Fe K-alpha Compton shoulder to the geometry and variability of the X-ray illumination of cosmic objects | In an X-ray reflection spectrum, a tail-like spectral feature generated via
Compton down-scattering, known as a Compton shoulder (CS), appears at the
low-energy side of the iron K$\alpha$ line. Despite its great diagnostic
potential, its use as a spectral probe of the reflector has been seriously
limited due to observa... | 1607.05385v1 |
2016-07-19 | Highly mobile carriers in orthorhombic phases of iron-based superconductors FeSe${}_{1-x}$S${}_{x}$ | The field and temperature dependencies of the longitudinal and Hall
resistivity have been measured for FeSe${}_{1-x}$S${}_{x}$ (x=0.04, 0.09 and
0.19) single crystals. The sample FeSe${}_{0.81}$S${}_{0.19}$ does not show a
transition to an orthorhombic phase and exhibits at low temperatures the
transport properties qui... | 1607.05669v2 |
2016-08-02 | Correlation of Fe-based Superconductivity and Electron-Phonon Coupling in an FeAs/Oxide Heterostructure | Interfacial phonons between iron-based superconductors (FeSCs) and perovskite
substrates have received considerable attention due to the possibility of
enhancing preexisting superconductivity. Using scanning tunneling spectroscopy,
we studied the correlation between superconductivity and e-ph interaction with
interfaci... | 1608.00886v4 |
2016-08-03 | Structure of spin excitations in heavily electron-doped Li0.8Fe0.2ODFeSe superconductors | Heavily electron-doped iron-selenide (HEDIS) high-transition-temperature
(high-$T_{\rm{c}}$) superconductors, which have no hole Fermi pockets, but have
a notably high $T_{\rm{c}}$, have challenged the prevailing $s$$_\pm$ pairing
scenario originally proposed for iron pnictides containing both electron and
hole pockets... | 1608.01204v2 |
2016-08-04 | Isotopic enrichment of forming planetary systems from supernova pollution | Heating by short-lived radioisotopes (SLRs) such as aluminum-26 and iron-60
fundamentally shaped the thermal history and interior structure of Solar System
planetesimals during the early stages of planetary formation. The subsequent
thermo-mechanical evolution, such as internal differentiation or rapid volatile
degassi... | 1608.01435v1 |
2016-08-29 | Universal Lower Limit on Vortex Creep in Superconductors | Superconductors are excellent testbeds for studying vortices, topological
excitations that also appear in superfluids, liquid crystals, and Bose-Einstein
condensates. Vortex motion can be disruptive; it can cause phase transitions,
glitches in pulsars, and losses in superconducting microwave circuits, and it
limits the... | 1608.08092v2 |
2016-09-01 | Influence of interstitial Fe to the phase diagram of Fe$_{1+y}$Te$_{1-x}$Se$_x$ single crystals | Superconductivity (SC) with the suppression of long-range antiferromagnetic
(AFM) order is observed in the parent compounds of both iron-based and cuprate
superconductors. The AFM wave vectors are bicollinear ($\pi$, 0) in the parent
compound FeTe different from the collinear AFM order ($\pi$, $\pi$) in most
iron pnict... | 1609.00105v1 |
2016-09-07 | Efficiency of Planetesimal Ablation in Giant Planetary Envelopes | Observations of exoplanetary spectra are leading to unprecedented constraints
on their atmospheric elemental abundances, particularly O/H, C/H, and C/O
ratios. Recent studies suggest that elemental ratios could provide important
constraints on formation and migration mechanisms of giant exoplanets. A
fundamental assump... | 1609.02143v1 |
2016-09-18 | Spintronics Detection of Interfacial Magnetic Switching in a Paramagnetic Tris(8-hydroxyquinoline)iron(III) Thin Film | Organic semiconductors find increasing importance in spin transport devices
due to the modulation and control of their properties through chemical
synthetic versatility. The organic materials are used as interlayers between
two ferromagnet (FM) electrodes in organic spin valves (OSV), as well as for
magnetic spin manip... | 1609.05421v1 |
2016-10-04 | Tomographic reflection modelling of quasi-periodic oscillations in the black hole binary H 1743-322 | Accreting stellar mass black holes (BHs) routinely exhibit Type-C
quasi-periodic oscillations (QPOs). These are often interpreted as
Lense-Thirring precession of the inner accretion flow, a relativistic effect
whereby the spin of the BH distorts the surrounding space-time, inducing nodal
precession. The best evidence f... | 1610.00948v1 |
2016-09-29 | Thin layered drawing media probed by THz time-domain spectroscopy | Dry and wet drawing materials were investigated by THz time-domain
spectroscopy in transmission mode. Carbon-based and iron-gall inks have been
studied, some prepared following ancient recipes and others using current
synthetic materials; a commercial ink was studied as well. We measured the THz
signals on thin film of... | 1610.01025v1 |
2016-10-31 | Chromium analogues of Iron-based superconductors | We theoretically investigate the $d^4$ (Cr$^{2+}$) compound BaCr$_2$As$_2$
and show that, despite non-negligible differences in the electronic structure,
its many-body physics mirrors that of BaFe$_2$As$_2$, which has instead a $d^6$
(Fe$^{2+}$) configuration. This reflects a symmetry of the electron correlation
effect... | 1610.10054v1 |
2016-11-17 | Deformation behaviour of body centered cubic iron nanopillars containing coherent twin boundaries | Molecular dynamics simulations were performed to understand the role of twin
boundaries on deformation behaviour of body-centred cubic (BCC) iron (Fe)
nanopillars. The twin boundaries varying from one to five providing twin
boundary spacing in the range 8.5 - 2.8 nm were introduced perpendicular to the
loading directio... | 1611.05575v1 |
2016-12-16 | Pressure-Induced Metallization in Iron-Based Ladder Compounds Ba$_{1-x}$Cs$_x$Fe$_2$Se$_3$ | Electrical resistivity measurements have been performed on the iron-based
ladder compounds Ba$_{1-x}$Cs$_x$Fe$_2$Se$_3$ ($x$ = 0, 0.25, 0.65, and 1)
under high pressure. A cubic anvil press was used up to 8.0 GPa, whereas
further higher pressure was applied using a diamond anvil cell up to 30.0 GPa.
Metallic behavior o... | 1612.05394v1 |
2016-12-29 | Molecular nucleation theory of dust formation in core-collapse supernovae applied to SN 1987A | We model dust formation in the core collapse supernova explosion SN 1987A by
treating the gas-phase formation of dust grain nuclei as a chemical process. To
compute the synthesis of fourteen species of grains we integrate a
non-equilibrium network of nucleating and related chemical reactions and follow
the growth of th... | 1612.09013v2 |
2017-01-11 | Antiferromagnetic structure and electronic properties of BaCr2As2 and BaCrFeAs2 | The chromium arsenides BaCr2As2 and BaCrFeAs2 with ThCr2Si2 type structure
(space group I4/mmm; also adopted by '122' iron arsenide superconductors) have
been suggested as mother compounds for possible new superconductors. DFT-based
calculations of the electronic structure evidence metallic antiferromagnetic
ground sta... | 1701.03127v1 |
2017-01-16 | Comprehensive Timing and X-ray Spectral Analysis of GX 1+4 | We present analysis of RXTE--PCA observations of GX 1+4 between March 3, 2001
and January 31, 2003 together with the CGRO--BATSE X-ray flux and frequency
derivative time series between 1991 and 1999. From the timing analysis of
RXTE-PCA observations, we are able to phase connect pulse arrival times of the
source within... | 1701.04328v2 |
2017-01-17 | Phase diagram and neutron spin resonance of superconducting NaFe$_{1-x}$Cu$_x$As | We use transport and neutron scattering to study the electronic phase diagram
and spin excitations of NaFe$_{1-x}$Cu$_x$As single crystals. Similar to Co-
and Ni-doped NaFeAs, a bulk superconducting phase appears near $x\approx2\%$
with the suppression of stripe-type magnetic order in NaFeAs. Upon further
increasing Cu... | 1701.04874v1 |
2017-01-20 | Tuning sizes, morphologies, and magnetic properties of mono- vs. multi-core iron oxide nanoparticles through control of added water in the polyol synthesis | The polyol route is a versatile and up-scalable method to produce large
batches of iron oxide nanoparticles with well-defined structure and magnetic
properties. Controlling parameters such as temperature and duration of
reaction, heating profile, nature of polyol solvent or of organometallic
precursors were reported in... | 1701.05858v3 |
2017-01-28 | Deep Recurrent Neural Network for Protein Function Prediction from Sequence | As high-throughput biological sequencing becomes faster and cheaper, the need
to extract useful information from sequencing becomes ever more paramount,
often limited by low-throughput experimental characterizations. For proteins,
accurate prediction of their functions directly from their primary amino-acid
sequences h... | 1701.08318v1 |
2017-02-28 | Neutrino Emission from Supernovae | Supernovae are the most powerful cosmic sources of MeV neutrinos. These
elementary particles play a crucial role when the evolution of a massive star
is terminated by the collapse of its core to a neutron star or a black hole and
the star explodes as supernova. The release of electron neutrinos, which are
abundantly pr... | 1702.08713v1 |
2017-03-24 | Role of the orbital degree of freedom in iron-based superconductors | Almost a decade has passed since the serendipitous discovery of the
iron-based high temperature superconductors (FeSCs) in 2008. The question of
how much similarity the FeSCs have with the copper oxide high temperature
superconductors emerged since the initial discovery of long-range
antiferromagnetism in the FeSCs in ... | 1703.08622v2 |
2017-07-04 | Blocking metal accretion onto population III stars by stellar wind | Low-mass population III (PopIII) stars of $\lesssim 0.8 M_{\odot}$ could
survive up until the present. Non-detection of low-mass PopIII stars in our
Galaxy has already put a stringent constraint on the initial mass function
(IMF) of PopIII stars, suggesting that PopIII stars have a top-heavy IMF. On
the other hand, som... | 1707.00989v1 |
2017-07-05 | Interactions between Coherent Twin Boundaries and Phase Transition of Iron under Dynamic Loading and Unloading | Under high pressures, phase transition, as well as deformation twins, are
constantly reported in many BCC metals, whose interactions are of fundamental
importance to understand strengthen mechanism of these metals under extreme
conditions. However, the interactions between twins and phase transition in BCC
metals are r... | 1707.01276v1 |
2017-07-06 | Phonon Spectra in the Parent Superconducting Iron-tuned Telluride Fe$_{1+x}$Te from Inelastic Neutron Scattering and Ab Initio Calculations | We report inelastic neutron scattering measurements of phonon spectra in the
parent superconductor iron-tuned chalcogenide Fe$_{1+x}$Te, for two different x
contents (x $\leq$ 0.11), using neutron time-of-flight technique. Thermal
neutron spectroscopy allowed to collect the low-temperature Stokes spectra over
an extend... | 1707.01970v2 |
2017-07-17 | Coupling of structure to magnetic and superconducting orders in quasi-one-dimensional $\text{K}_2\text{Cr}_3\text{As}_3$ | Quasi-one-dimensional $A_2\text{Cr}_3\text{As}_3$ (with $A = \text{K, Cs,
Rb}$) is an intriguing new family of superconductors which exhibit many similar
features to the cuprate and iron-based unconventional superconductor families.
Yet in contrast to these systems, no charge or magnetic ordering has been
observed whic... | 1707.05286v1 |
2017-07-20 | Nuclear absorption and emission in the AGN merger NGC 6240: the hard X-ray view | We present the analysis of four NuSTAR observations of the luminous infrared
galaxy merger NGC 6240, hosting a close pair of highly obscured active galactic
nuclei (AGN). Over a period of about two years, the source exhibits hard X-ray
variability of the order of 20 per cent, peaking around 20 keV. When the two
AGN are... | 1707.07613v1 |
2017-08-18 | Superconductivity across Lifshitz transition and anomalous insulating state in surface K-dosed (Li0.8Fe0.2OH)FeSe | In the iron-based superconductors, understanding the relation between
superconductivity and electronic structure upon doping is crucial for exploring
the pairing mechanism. Recently it was found that in iron selenide (FeSe),
enhanced superconductivity (Tc over 40K) can be achieved via electron doping,
with the Fermi su... | 1708.05635v1 |
2017-09-01 | Two-dimensional Massless Dirac Fermions in Antiferromagnetic AFe2As2 (A = Ba, Sr) | We report infrared studies of AFe$_{2}$As$_{2}$ (A = Ba, Sr), two
representative parent compounds of iron-arsenide superconductors, at magnetic
fields (B) up to 17.5 T. Optical transitions between Landau levels (LLs) were
observed in the antiferromagnetic states of these two parent compounds. Our
observation of a $\sqr... | 1709.00203v1 |
2017-09-08 | Machine learning modeling of superconducting critical temperature | Superconductivity has been the focus of enormous research effort since its
discovery more than a century ago. Yet, some features of this unique phenomenon
remain poorly understood; prime among these is the connection between
superconductivity and chemical/structural properties of materials. To bridge
the gap, several m... | 1709.02727v2 |
2017-09-15 | Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material | Anisotropy effects on flux pinning and flux flow are strongly effective in
cuprate as well as iron-based superconductors due to their intrinsically
layered crystallographic structure. However $\textrm{Fe(Se,Te)}$ thin films
grown on $\textrm{CaF}_2$ substrate result less anisotropic with respect to all
the other iron b... | 1709.05089v3 |
2017-10-04 | Surface abundance and the hunt for stratification in chemically peculiar hot subdwarfs: PG 0909+276 and UVO 0512-08 | Edelmann (2003) identified two chemically peculiar hot subdwarfs, PG 0909+276
and UVO 0512-08, as having very high overabundances of iron-group elements. We
obtained high-resolution ultraviolet spectroscopy in order to measure
abundances of species not observable in the optical, and to seek evidence for
chemical strati... | 1710.01663v1 |
2017-10-18 | Using MRI Cell Tracking to Monitor Immune Cell Recruitment in Response to a Peptide-Based Cancer Vaccine | Purpose: MRI cell tracking can be used to monitor immune cells involved in
the immunotherapy response, providing insight into the mechanism of action,
temporal progression of tumour growth and individual potency of therapies. To
evaluate whether MRI could be used to track immune cell populations in response
to immunoth... | 1710.06817v1 |
2017-11-02 | Constraining planet structure and composition from stellar chemistry: trends in different stellar populations | The chemical composition of stars that have orbiting planets provides
important clues about the frequency, architecture, and composition of exoplanet
systems. We explore the possibility that stars from different galactic
populations that have different intrinsic abundance ratios may produce planets
with a different ove... | 1711.00777v1 |
2017-11-08 | Matrix-assisted fabrication and exotic charge mobility of (Li,Fe)OHFeSe superconductor films | Superconducting (Li1-xFex)OHFe1-ySe films are attractive for both the basic
research and practical application. However, the conventional vapor deposition
techniques are not applicable in synthesizing the films of such a complex
system. So no intrinsic charge transport measurements on the films are
available so far to ... | 1711.02920v1 |
2017-11-17 | Nematic superconducting state in iron pnictide superconductors | Nematic order often breaks the tetragonal symmetry of iron-based
superconductors. It arises from regular structural transition or electronic
instability in the normal phase. Here, we report the observation of a nematic
superconducting state, by measuring the angular dependence of the in-plane and
out-of-plane magnetore... | 1711.06383v1 |
2017-11-17 | Frustrated magnetism in tetragonal CoSe, analogue to superconducting FeSe | Recently synthesized metastable tetragonal CoSe, isostructural to the FeSe
superconductor, offers a new avenue for investigating systems in close
proximity to the iron-based superconductors. We present magnetic and transport
property measurements on powders and single crystals of CoSe. High field
magnetic susceptibilit... | 1711.06725v2 |
2017-11-21 | The X-ray footprint of the CircumNuclear Disk | We studied the central regions of the Galactic Centre to determine if the
CircumNuclear Disk (CND) acts as an absorber or a barrier for the central
X-rays diffuse emission. After reprocessing 4.6Ms of Chandra observations, we
were able to detect, for the first time, a depression in the X-ray luminosity
of the diffuse e... | 1711.07841v1 |
2017-11-28 | SFXTs versus classical SgXBs: Does the difference lie in the companion wind? | We present a comparative study of stellar winds in classical supergiant high
mass X-ray binaries (SgXBs) and supergiant fast X-ray transients (SFXTs) based
on the analysis of publicly available out-of-eclipse observations performed
with Suzaku and XMM-Newton. Our data-set includes 55 observations of classical
SgXBs and... | 1711.10510v3 |
2017-12-04 | Chemical fingerprints of hot Jupiter planet formation | The current paradigm to explain the presence of Jupiters with small orbital
periods (P $<$ 10 days; hot Jupiters) that involves their formation beyond the
snow line following inward migration, has been challenged by recent works that
explored the possibility of in situ formation. We aim to test whether stars
harbouring... | 1712.01035v2 |
2017-12-04 | Protonation induced high-Tc phases in iron-based superconductors evidenced by NMR and magnetization measurements | Chemical substitution during growth is a well-established method to
manipulate electronic states of quantum materials, and leads to rich spectra of
phase diagrams in cuprate and iron-based superconductors. Here we report a
novel and generic strategy to achieve nonvolatile electron doping in series of
(i.e. 11 and 122 s... | 1712.01191v4 |
2017-12-06 | Constraining the final fates of massive stars by oxygen and iron enrichment history in the Galaxy | Recent observational studies of core-collapse supernovae suggest only stars
with zero-age main sequence masses smaller than $16$-$18\ M_\odot$ explode when
they are red supergiants, producing type IIP supernovae. This may imply that
more massive stars produce other types of supernovae or they simply collapse to
black h... | 1712.02013v1 |
2017-12-06 | Interaction of the accretion flows in corona and disk near the black hole in AGN | Accretion flows toward black holes can be of a quite different nature,
described as an optically thick cool gas flow in a disk for high accretion
rates or as a hot coronal optically thin gas flow for low accretion rates,
possibly affected by outflowing gas. The detection of broad iron emission lines
in active galactic ... | 1712.02031v1 |
2017-12-24 | Search For Gravitational Redshifted Absorption Lines In LMXB Serpens X-1 | The equation of state for ultra-dense matter can be tested from observations
of the ratio of mass to radius of neutron stars. This could be measured
precisely from the redshift of a narrow line produced on the surface. X-rays
bursts have been intensively searched for such features, but so far without
detection. Here in... | 1712.08918v1 |
2018-01-09 | Diverse fluctuations and anisotropic Gr{\" u}neisen parameter behavior in iron-based superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ and their correlation with superconductivity | In this study, the temperature dependence of elastic constants $C_{11}$,
$C_{33}$, $C_{\rm E} = (C_{11}-C_{12})/2$, $C_{66}$ and $C_{44}$ of the
iron-based superconductor Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ (0 $\leqq x
\leqq$ 0.245) have been measured. This system shows a large elastic softening
in $C_{66}$ towards lo... | 1801.02791v1 |
2018-01-13 | Advanced first-principles theory of superconductivity including both lattice vibrations and spin fluctuations: The case of FeB$_4$ | We present an advanced method to study spin fluctuations in superconductors
quantitatively, and entirely from first principles. This method can be
generally applied to materials where electron-phonon coupling and spin
fluctuations coexist. We employ it here to examine the recently synthesized
superconductor iron tetrab... | 1801.04421v1 |
2018-01-15 | Unconventional Charge Density Wave Order in the Pnictide Superconductor Ba(Ni$_{1-x}$Co$_x$)$_2$As$_2$ | Ba(Ni$_{1-x}$Co$_x$)$_2$As$_2$ is a structural homologue of the pnictide high
temperature superconductor, Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, in which the Fe
atoms are replaced by Ni. Superconductivity is highly suppressed in this
system, reaching a maximum $T_c$ = 2.3 K, compared to 24 K in its iron-based
cousin, and the ... | 1801.04874v2 |
2018-01-26 | Models for the Unusual Supernova iPTF14hls | Supernova iPTF14hls maintained a bright, variable luminosity for more than
600 days, while lines of hydrogen and iron in its spectrum had different
speeds, but showed little evolution. Here several varieties of models are
explored for iPTF14hls-like events. They are based upon circumstellar medium
(CSM) interaction in ... | 1801.08666v1 |
2018-03-01 | Hydrogen Diffusion and Trapping in α-Iron: The Role of Quantum and Anharmonic Fluctuations | We investigate the thermodynamics and kinetics of a hydrogen interstitial in
magnetic {\alpha}-iron, taking account of the quantum fluctuations of the
proton as well as the anharmonicities of lattice vibrations and hydrogen
hopping. We show that the diffusivity of hydrogen in the lattice of BCC iron
deviates strongly f... | 1803.00600v1 |
2018-03-02 | Topological Dirac semimetal phase in the iron-based superconductor Fe(Te,Se) | Topological Dirac semimetals (TDSs) exhibit bulk Dirac cones protected by
time reversal and crystal symmetry, as well as surface states originating from
non-trivial topology. While there is a manifold possible onset of
superconducting order in such systems, few observations of intrinsic
superconductivity have so far be... | 1803.00845v1 |
2018-03-20 | Further insight on the hypervelocity white dwarf, LP 40-365 (GD 492): a nearby emissary from a single-degenerate Type Ia supernova | The recently discovered hypervelocity white dwarf LP 40-65 (aka GD 492) has
been suggested as the outcome of the failed disruption of a white dwarf in a
sub-luminous Type Ia supernova (SN Ia). We present new observations confirming
GD 492 as a single star with unique spectral features. Our spectroscopic
analysis sugges... | 1803.07564v1 |
2018-04-07 | Bare and Polymer Coated Iron Oxide Superparamagnetic Nanoparticles for Effective Removal of U (VI) from Acidic and Neutral Aqueous Medium | Superparamagnetic {\gamma}-Fe2O3 nanoparticles (5 nm diameter) were
synthesized in water. The bare particles exhibit good colloidal stability at ~
pH 2 because of the strong electrostatic repulsion with a surface charge of +25
mV. The polyacrylic acid (PAA)-coated particles exhibit remarkable colloidal
stability at ~ p... | 1804.02522v1 |
2018-04-10 | Absence of superconductivity in iron polyhydrides at high pressures | Recently, C. M. P\'epin \textit{et al.} [Science \textbf{357}, 382 (2017)]
reported the formation of several new iron polyhydrides FeH$_x$ at pressures in
the megabar range, and spotted FeH$_5$, which forms above 130 GPa, as a
potential high-\tc \ superconductor, because of an alleged layer of dense
metallic hydrogen. ... | 1804.03572v2 |
2018-04-13 | A Long Serendipitous XMM-Newton Observation of the Intermediate Polar XY Ari | XY Ari is one of the few known eclipsing intermediate polars. We present
results from a detailed analysis of an unpublished archival observation using
XMM-Newton EPIC pn and MOS data in a quiescent state of XY Ari. The X-ray
orbital modulation and spin pulse variations were investigated for energy
dependent modulations... | 1804.04825v1 |
2018-04-23 | Spectral and Timing Properties of Atoll Source 4U 1705-44 : LAXPC/AstroSat Results | In this paper, we present the first results of spectral and timing properties
of the atoll source 4U 1705-44 using $\sim$ 100 ks data obtained with Large
Area X-ray Proportional Counter (LAXPC) onboard {\it AstroSat}. The source was
in the high-soft state during our observations and traced out a {\it banana
track} in t... | 1804.08371v1 |
2018-05-10 | A Tale of Two Metals: contrasting criticalities in the pnictides and hole-doped cuprates | The iron-based high temperature superconductors share a number of
similarities with their copper-based counterparts, such as reduced
dimensionality, proximity to states of competing order, and a critical role for
3d electron orbitals. Their respective temperature-doping phase diagrams also
contain certain commonalities... | 1805.03866v1 |
2018-05-10 | Stabilization of $s$-wave superconductivity through arsenic $p$-orbital hybridization in electron-doped BaFe$_2$As$_2$ | Using random-phase approximation spin-fluctuation theory, we study the
influence of the hybridization between iron $d$-orbitals and pnictide
$p$-orbitals on the superconducting pairing state in iron-based
superconductors. The calculations are performed for a 16-orbital Hubbard-Hund
tight-binding model of BaFe$_2$As$_2$... | 1805.04181v2 |
2018-05-30 | Tracking the Iron K$α$ line and the Ultra Fast Outflow in NGC 2992 at different accretion states | The Seyfert 2 galaxy NGC 2992 has been monitored eight times by XMM-Newton in
2010 and then observed again in 2013, while in 2015 it was simultaneously
targeted by Swift and NuSTAR. XMM-Newton always caught the source in a faint
state (2-10 keV fluxes ranging from 0.3 to 1.6$\times10^{-11}$ erg cm$^{-2}$
s$^{-1}$) but ... | 1805.12149v1 |
2018-06-04 | Towards a systematically improvable many-body description of antiferromagnetic iron oxide | We report variational and fixed-node diffusion quantum Monte Carlo (QMC)
calculations of anti-ferromagnetic iron oxide (FeO) in the ground state B1
crystal structure. The goal of this study was a systematic investigation of the
sensitivity of several ground state properties to a variety of QMC wave
function generation ... | 1806.01383v2 |
2018-09-04 | Anomalous peak effect in iron-based superconductors Ba$_{1-x}$K$_x$Fe$_2$As$_2$ ($x \approx$ 0.69 and 0.76) for magnetic-field directions close to the $ab$ plane and its possible relation to the spin paramagnetic effect | We report magnetic torque measurements on iron-pnictide superconductors
Ba$_{1-x}$K$_x$Fe$_2$As$_2$ ($x \approx$ 0.69 and 0.76) up to an applied field
of $B_a$ = 45 T. The peak effect is observed in torque-vs-field curves below
the irreversibility field. It is enhanced and becomes asymmetric as the field
is tilted from... | 1809.00762v3 |
2018-09-07 | Electron-magnon scattering in elementary ferromagnets from first principles: lifetime broadening and band anomalies | We study the electron-magnon scattering in bulk Fe, Co, and Ni within the
framework of many-body perturbation theory implemented in the full-potential
linearized augmented-plane-wave method. To this end, a $\mathbf{k}$-dependent
self-energy ($GT$ self-energy) describing the scattering of electrons and
magnons is constr... | 1809.02395v2 |
2018-09-21 | Electronic Spin transition in FeO$_{2}$: evidence for Fe(II) with peroxide O$_{2}^{2-}$ | The discovery of FeO$_{2}$ containing more oxygen than hematite
(Fe$_{2}$O$_{3}$) that was previously believed to be the most oxygen rich iron
compounds, has important implications on the study of the deep lower mantle
compositions. Compared to other iron compounds, there are limited reports on
FeO$_{2}$ making studies... | 1809.07969v1 |
2018-09-24 | The Variable Relativistic Outflow of IRAS 13224-3809 | The discovery of an ultrafast outflow has been reported in the z=0.0658
narrow line Seyfert galaxy IRAS 13224-3809 (Parker et al. 2017a). The ultrafast
outflow was first inferred through the detection of highly blueshifted
absorption lines (Parker et al. 2017a) and then confirmed with a principal
component analysis (PC... | 1809.09138v1 |
2018-11-06 | Energy scale of nematic ordering in the parent iron-based superconductor:BaFe2As2 | Nematicity plays an important role in the physics of iron-based
superconductors (IBS). Its microscopic origin and in particular its importance
for the mechanism of high-temperature superconductivity itself are highly
debated. A crucial knowledge in this regard is the degree to which the nematic
order influences the ele... | 1811.02430v2 |
2018-11-14 | Giant anisotropy in superconducting single crystals of CsCa$_2$Fe$_4$As$_4$F$_2$ | CsCa$_2$Fe$_4$As$_4$F$_2$ is a newly discovered iron-based superconductor
with $T_\mathrm{c}\sim$ 30 K containing double Fe$_2$As$_2$ layers that are
separated by insulating Ca$_2$F$_2$ spacer layers. Here we report the transport
and magnetization measurements on CsCa$_2$Fe$_4$As$_4$F$_2$ single crystals
grown for the ... | 1811.05706v1 |
2018-12-04 | Adsorption and dissociation of iron phthalocyanine on H/Si(111): Impact of van-der-Waals interactions and perspectives for subsurface doping | The adsorption of iron phthalocyanine (FePc) on the passivated H/Si(111)
surface is explored from first principles. We find that the organic molecule is
predominantly physisorbed with a distance to the surface of $2.6 \pm 0.1$
Angstrom, but also exhibits sizable resonance with the underlying substrate.
This establishes... | 1812.01639v3 |
2018-12-06 | Artificially Engineered Nanostrain in Iron Chalcogenide Superconductor Thin Film for Enhancing Supercurrent | Although nanoscale deformation, such as nanostrain in iron chalcogenide
(FeSexTe1-x, FST) thin films, has attracted attention owing to the enhancement
of general superconducting properties, including critical current density (Jc)
and critical transition temperature, its formation has proven to be an
extremely challengi... | 1812.02380v3 |
2018-12-13 | Emergent XY electronic nematicity in iron-based superconductors | Electronic nematicity, a correlated state that spontaneously breaks
rotational symmetry, is observed in several layered quantum materials. In
contrast to their liquid-crystal counterparts, the nematic director cannot
usually point in an arbitrary direction (XY nematics), but is locked by the
crystal to discrete directi... | 1812.05267v2 |
2018-12-13 | Visualizing the Nonlinear Coupling between Strain and Electronic Nematicity in the Iron Pnictides by Elasto-Scanning Tunneling Spectroscopy | Mechanical strain is a powerful technique for tuning electronic structure and
interactions in quantum materials. In a system with tetragonal symmetry, a
tunable uniaxial in-plane strain can be used to probe nematic correlations in
the same way that a tunable magnetic field is used to probe magnetic
correlations. Here, ... | 1812.05287v1 |
2018-12-20 | The long-term evolution and appearance of Type Iax postgenitor stars | Type Iax supernovae may arise from failed explosions of white dwarfs that
leave behind a bound remnant (i.e., a "postgenitor" star) that could be
identified in wide field surveys. To understand their observational signatures,
we simulate these white dwarf (WD) postgenitors from shortly after explosion
until they move b... | 1812.08793v2 |
2019-02-14 | Photoionization Emission Models for the Cyg X-3 X-ray Spectrum | We present model fits to the X-ray line spectrum of the well known High Mass
X-ray binary Cyg X-3. The primary observational dataset is a spectrum taken
with the $Chandra$ X-ray Observatory High Energy Transmission Grating (HETG) in
2006, though we compare it to all the other observations of this source taken
so far by... | 1902.05589v3 |
2019-02-28 | Quantum phase transition inside the superconducting dome of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ probed by optical magneto-sensing using NV-centers in diamond | While unusual normal state properties, such as non-Fermi liquid behavior of
the resistivity, are commonly associated with strong quantum fluctuations,
evidence for its presence inside the superconducting dome are much scarcer. In
this paper, we use sensitive and minimally invasive optical magnetometry based
on NV-cente... | 1903.00053v2 |
2019-03-01 | Observations of the Ultraviolet-Bright Star Barnard 29 in the Globular Cluster M13 (NGC 6205) | We have analyzed FUSE, COS, GHRS, and Keck HIRES spectra of the UV-bright
star Barnard 29 in M13 (NGC 6205). By comparing the photospheric abundances
derived from multiple ionization states of C, N, O, Si, and S, we infer an
effective temperature T_eff = 21,400 +/- 400 K. Balmer-line fits yield a
surface gravity log g ... | 1903.00350v1 |
2019-03-04 | Structural and magnetic properties in sputtered iron oxide epitaxial thin films -- Magnetite Fe$_3$O$_4$ and epsilon ferrite e-Fe$_2$O$_3$ | Epitaxial thin film fabrication of iron oxides including magnetite Fe3O4 and
epsilon-ferrite epsilon-Fe2O3 with the potential for advancing electromagnetic
devices has been investigated, which led to the first ever epsilon-ferrite
epitaxial layer being synthesized in the conventional sputtering process.
Concerning Fe3O... | 1903.01022v1 |
2019-03-11 | The Nematic Energy Scale and the Missing Electron Pocket in FeSe | Superconductivity emerges in proximity to a nematic phase in most iron-based
superconductors. It is therefore important to understand the impact of
nematicity on the electronic structure. Orbital assignment and tracking across
the nematic phase transition prove to be challenging due to the multiband
nature of iron-base... | 1903.04557v2 |
2019-03-14 | 3D visualizations of nano-scale phase separation and ultrafast dynamic correlation between phases in (Na0.32K0.68)0.95Fe1.75Se2 | Phase separation of metallic and antiferromagnetic (AFM) insulating phases in
alkaline iron selenides (AxFe2-ySe2) continues to attract intense interest
because the relationship between two peculiar features probably is a key to
clarifying the pairing mechanism of AxFe2-ySe2 superconductors. Here we report
that the 3D ... | 1903.05797v1 |
2019-03-15 | Band-selective clean- and dirty-limit superconductivity with nodeless gaps in the bilayer iron-based superconductor CsCa$_2$Fe$_4$As$_4$F$_2$ | The optical properties of the new iron-based superconductor
CsCa$_2$Fe$_4$As$_4$F$_2$ with $T_c \sim 29$~K have been determined. In the
normal state a good description of the low-frequency response is obtained with
a superposition of two Drude components of which one has a very low scattering
rate (narrow Drude-peak) a... | 1903.06466v1 |
2019-05-07 | Single-parameter scaling in the magnetoresistance of optimally doped La$_{2-x}$Sr$_{x}$CuO$_4$ | We show that the recent magnetoresistance data on thin-film
La$_{2-x}$Sr$_{x}$CuO$_4$ (LSCO) in strong magnetic fields ($B$) obeys a
single-parameter scaling of the form MR$(B,T)=f(\mu_H(T)B)$, where
$\mu_H^{-1}(T)\sim T^{\alpha}$ ($1\le\alpha\le2$), from $T=180$K until
$T\sim20$K, at which point the single-parameter s... | 1905.02737v1 |
2019-05-13 | Kinetics of phase separation, border of miscibility gap in Fe-Cr and limit of Cr solubility in iron at 832 K | Kinetics of phase decomposition accompanied by precipitation of sigma-phase
in a Fe73.7Cr26.3 alloy isothermally annealed at 832 K was studied by means of
M\"ossbauer spectroscopy. Two stage decomposition process has been revealed by
three different quantities viz. the average hyperfine field, <H>, the
short-range para... | 1905.05156v1 |
2019-05-24 | The empirical aspects of Eliashberg formalism for the superconducting mechanism in Iron-based superconductors | We have investigated experimentally how properties of NdFeAsO0.8F0.2
superconductor affected due to the substitution of the Ca2+/Nd3+ doping. Based
on the XRD data refinement, various structural parameters such as lattice
parameters, bond angles, bond length, and etc. were studied. We have determined
the upper limit of... | 1905.11378v1 |
2019-05-28 | Photo-induced Superconducting State with Long-lived Disproportionate Band Filling in FeSe | Photo-excitation is a very powerful way to instantaneously drive a material
into a novel quantum state without any fabrication, and variable ultrafast
techniques have been developed to observe how electron-, lattice-, and
spin-degrees of freedom change. One of the most spectacular phenomena is
photo-induced superconduc... | 1905.12138v1 |
2019-05-29 | Photoinduced nematic state in FeSe$_{0.4}$Te$_{0.6}$ | FeSe$_{x}$Te$_{1-x}$ compounds present a complex phase diagram, ranging from
the nematicity of FeSe to the $(\pi, \pi)$ magnetism of FeTe. We focus on
FeSe$_{0.4}$Te$_{0.6}$, where the nematic ordering is absent at equilibrium. We
use a time-resolved approach based on femtosecond light pulses to study the
dynamics foll... | 1905.12448v1 |
2019-05-30 | Quantum dynamics of hydrogen in iron-based superconductor LaFeAsO0.9D0.1 measured with inelastic neutron spectroscopy | Inelastic neutron scattering was performed for an iron-based superconductor
LaFeAsO0.9D0.1, where most of D (deuterium) replaces oxygen, while a tiny
amount goes into interstitial sites. By first-principle calculation, we
characterize the interstitial sites for D (and for H slightly mixed) with four
equivalent potentia... | 1905.12826v2 |
2019-05-30 | Changes in long-term properties of the Danube river level and flow induced by damming | In this paper we assessed changes in scaling properties of the river Danube
level and flow data, associated with building of Djerdap/Iron Gates
hydrological power plants positioned on the border of Romania and Serbia. We
used detrended fluctuation analysis (DFA), wavelet transform spectral analysis
(WTS) and wavelet-ba... | 1905.13144v2 |
2019-08-06 | FeOOH instability at the lower mantle conditions | Goethite, {\alpha}-FeOOH, is a major component among oxidized iron species,
called rust, which formed as a product of metabolism of anoxygenic prokaryotes
(1, 2) inhabiting the Earth from about 3.8 billion years (Gy) ago until the
Great Oxidation Event (GOE) of about 2.5 Gy ago. The rust was buried on the
ocean floor (... | 1908.02114v1 |
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