publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2023-05-12 | Impact of errors in the magnetic field measurement on the precision determination of neutrino oscillation parameters at the proposed ICAL detector at INO | The magnetised iron calorimeter (ICAL) detector proposed at the India-based
Neutrino Observatory will be a 51 kton detector made up of 151 layers of 56 mm
thick soft iron with 40 mm air gap in between where the RPCs, the active
detectors, will be placed. The main goal of ICAL is to make precision
measurements of the ne... | 2305.07291v2 |
2023-06-16 | Tailoring defects and nanocrystal transformation for optimal heating power in bimagnetic $Co_yFe_{1-y}O@Co_xFe_{3-x}O_4$ particles | The effects of cobalt incorporation in spherical heterostructured iron oxide
nanocrystals (NCs) of sub-critical size have been explored by colloidal
chemistry methods. Synchrotron X-ray total scattering methods suggest that
cobalt (Co) substitution in rock salt iron oxide NCs tends to remedy its vacant
iron sites, offe... | 2306.09684v1 |
2023-06-22 | Studying the mass sensitivity of air-shower observables using simulated cosmic rays | Using CORSIKA simulations, we investigate the mass sensitivity of cosmic-ray
air-shower observables for sites at the South Pole and Malarg\"ue, Argentina,
the respective locations of the IceCube Neutrino Observatory and the Pierre
Auger Observatory. Exact knowledge of observables from air-shower simulations
was used to... | 2306.13246v2 |
2023-07-19 | Efficiency, Accuracy, and Transferability of Machine Learning Potentials: Application to Dislocations and Cracks in Iron | Machine learning interatomic potentials (ML-IAPs) enable quantum-accurate,
classical molecular dynamics simulations of large systems, beyond reach of
density functional theory (DFT). Yet, their efficiency and ability to predict
systems larger than DFT supercells are not fully explored, posing a question
regarding trans... | 2307.10072v2 |
2023-11-12 | Star Formation in Self-gravitating Disks in Active Galactic Nuclei. III. Efficient Production of Iron and Infrared Spectral Energy Distributions | Strong iron lines are a common feature of the optical spectra of active
galactic nuclei (AGNs) and quasars from $z\sim 6-7$ to the local Universe, and
[Fe/Mg] ratios do not show cosmic evolution. During active episodes, accretion
disks surrounding supermassive black holes (SMBHs) inevitably form stars in the
self-gravi... | 2311.06782v1 |
2024-01-18 | The 2022 Outburst of IGR J17091-3624: Connecting the exotic GRS 1915+105 to standard black hole X-ray binaries | While the standard X-ray variability of black hole X-ray binaries (BHXBs) is
stochastic and noisy, there are two known BHXBs that exhibit exotic
`heartbeat'-like variability in their light curves: GRS 1915+105 and IGR
J17091-3624. In 2022, IGR J17091-3624 went into outburst for the first time in
the NICER/NuSTAR era. T... | 2401.10192v1 |
2024-03-15 | Asteroid reflectance spectra from Gaia DR3: Near-UV in primitive asteroids | In the context of charge-coupled devices (CCDs), the ultraviolet (UV) region
has mostly remained unexplored after the 1990s. Gaia DR3 offers the community a
unique opportunity to explore tens of thousands of asteroids in the near-UV as
a proxy of the UV absorption. This absorption has been proposed in previous
works as... | 2403.10321v1 |
1993-01-29 | A Possible Forest of Emission Lines from Proto-galaxies | The possibility of detecting proto-galaxies in the UV band is pointed out,
assuming that galaxy formation occured at z $\sim 5-6$. It is shown that the
diffuse gas in collapsing galaxy sized objects with temperatures $\sim
10^{6\pm0.5}$ K, and with a modest amount of metallicity, should copiously
produce emission lines... | 9301012v1 |
1995-10-23 | X-ray spectra from convective photospheres of neutron stars | We present first results of modeling convective photospheres of neutron
stars. We show that in photospheres composed of the light elements convection
arises only at relatively low effective temperatures (< 3-5*10^4 K), whereas in
the case of iron compositon it arises at < 3*10^ K. Convection changes the
depth dependenc... | 9510116v2 |
1997-01-22 | Two-phase pair corona model for AGN: physical modelling and diagnostics | The predictions of the two-phase accretion disc-corona models for active
galactic nuclei are compared with observations. We discuss the possibility to
use X-ray spectral slopes, equivalent widths of the iron line, and the observed
flux-spectral index correlation as diagnostics of the X/gamma-ray source
compactness and ... | 9701168v1 |
1997-03-04 | RXTE Observation of the Seyfert 2 Galaxy NGC4507 | Preliminary results of the RXTE observation of the Seyfert 2 Galaxy NGC4507
are presented. The observed broadband [4-100 keV] spectrum is intrinsically
hard (Gamma = 1.2); an iron line is detected with a relatively high equivalent
width (EW = 400 eV). The remaining calibration uncertanties are briefly
discussed, as wel... | 9703019v1 |
1997-05-12 | The most Distant [OIII]-emitting Quasar PKS 1937-101 at redshift 3.8 | We report the discovery of a high-z quasar with unambiguous [OIII]5007
emission; PKS 1937-101 at redshift 3.8. This quasar, however, shows little
evidence for rest-frame ultraviolet and optical FeII emission. It is thus shown
that PKS 1937-101 does not belong to a class of super iron-rich high-z quasars
reported by Els... | 9705075v1 |
1997-08-08 | A depression before a bump in the highest energy cosmic ray spectrum | We re-examine the interaction of ultra high energy nuclei with the microwave
background radiation. We find that the giant dipole resonance leaves a new
signature in the differential energy spectrum of iron sources located around 3
Mpc: A depression before the bump which is followed by the expected cutoff. | 9708082v2 |
1997-10-07 | Fe I line shifts in the optical spectrum of the Sun | New improvements in the measurement of both the optical solar spectrum and
laboratory wavelengths for lines of neutral iron are combined to extract
central wavelength shifts for 1446 lines observed in the Sun. This provides the
largest available database of accurate solar wavelengths useful as a reference
for compariso... | 9710066v1 |
1998-05-15 | The double-lined spectroscopic binary alpha Andromedae: orbital elements and elemental abundances | We performed a spectroscopic study of the SB2 Mercury-Manganese star alpha
And. Our measurements of the secondary's radial velocities result in improved
orbital elements. The secondary shows abundances typical of the metallic-line
stars: a Ca deficiency, small overabundances of the iron-peak elements, and 1.0
dex overa... | 9805205v1 |
1998-05-27 | Strong gravity and X-ray spectroscopy | This paper reviews the effects of general relativity in an X-ray spectrum
reflected from a cold matter accreting onto a black hole. The spectrum consists
of the iron K$\alpha$ line and the Compton reflection. We sketch the overall
picture of radiative processes in the central parts of the accretion flow with
relation t... | 9805328v1 |
1999-05-25 | First results on characterization of Cerenkov images through combined use of Hillas, fractal and wavelet parameters | Based on Monte Carlo simulations using the CORSIKA code, it is shown that
Cerenkov images produced by ultrahigh energy $\gamma$-rays and cosmic ray
nuclei (proton, Neon and Iron) are fractal in nature. The resulting
multifractal and wavelet moments when employed in association with the
conventional Hillas parameters as... | 9905312v1 |
1999-11-24 | Discovery of molecular hydrogen in a high-velocity cloud of the Galactic halo | We report the discovery of molecular hydrogen absorption in a Galactic
high-velocity cloud (HVC) in the direction of the Large Magellanic Cloud. For
the same HVC we derive an iron abundance which is half of the solar value.
Thus, all evidence points to a Galactic origin for high-velocity cloud complex
in front of the L... | 9911455v1 |
1999-11-30 | Prompt Iron Enrichment, Two r-Process Components, and Abundances in Very Metal-Poor Stars | We present a model to explain the wide range of abundances for heavy
r-process elements (mass number A > 130) at low [Fe/H]. This model requires
rapid star formation and/or an initial population of supermassive stars in the
earliest condensed clots of matter to provide a prompt or initial Fe inventory.
Subsequent Fe an... | 9911526v1 |
2000-03-29 | A Comparative Study of the Depth of Maximum of Simulated Air Shower Longitudinal Profiles | A comparative study of simulated air shower longitudinal profiles is
presented. An appropriate thinning level for the calculations is first
determined empirically. High statistics results are then provided, over a wide
energy range, (10^14.0 to 10^20.5 eV), for proton & iron primaries, using four
combinations of the MO... | 0003442v2 |
2000-04-20 | X-rays from Radio-Galaxies: BeppoSAX Observations | We briefly review BeppoSAX observations of X-ray bright radio-galaxies. Their
X-ray spectra are quite varied, and perhaps surprisingly, any similarity
between radio-loud AGN and Seyfert galaxies is the exception rather than the
rule. When detected, reprocessing features (iron line and reflection) are
generally weak, su... | 0004291v1 |
2000-05-08 | Properties of Warm absorbers in Narrow-Line Seyfert 1 galaxies | We present a study of the X-ray properties of several NLS1 galaxies, focusing
on their warm absorbers. In the first part, we discuss properties of dusty and
dust-free warm absorbers in NLS1s, and study their potential contribution to
high-ionization optical iron lines. In the second part, we summarize our work
on the e... | 0005172v1 |
2000-06-05 | A pot of gold at the end of the cosmic "raynbow"? | We critically review the common belief that ultrahigh energy cosmic rays are
protons or atomic nuclei with masses not exceeding that of iron. We find that
heavier nuclei are indeed possible, and discuss possible sources and
acceleration mechanisms for such primaries. We also show detailed simulations
of extensive air s... | 0006071v1 |
2000-06-19 | Abundances and Kinematics of Field Halo and Disk Stars I: Observational Data and Abundance Analysis | We describe observations and abundance analysis of a high-resolution,
high-S/N survey of 168 stars, most of which are metal-poor dwarfs. We follow a
self-consistent LTE analysis technique to determine the stellar parameters and
abundances, and estimate the effects of random and systematic uncertainties on
the resulting... | 0006260v1 |
2000-09-18 | Age-metallicity relation and Chemical evolution of the LMC from UVES spectra of Globular Cluster giants | We report on the first high-resolution spectroscopy of 10 giants in LMC
Globular Clusters in a wide age range, obtained with the newly commissioned
spectrograph UVES at VLT UT2. These observations are used to derive oxygen and
iron content of these clusters, and the abundances are then used to cast a more
precise view,... | 0009273v1 |
2000-09-20 | The BeppoSAX observation of Mrk 766 | The Narrow Line Seyfert 1 galaxy Mrk 766 has been observed by BeppoSAX on May
1997. The source was fairly variable, both in flux and spectrum, during the
observation. The variability is the largest around 2 keV, possibly due to
variations in the warm absorber properties. An oxygen line is clearly detected,
at least in ... | 0009322v1 |
2000-11-24 | Lithium-Beryllium-Boron and Oxygen in the early Galaxy | Oxygen is a much better evolutionary index than iron to follow the history of
Lithium-Beryllium-Boron (LiBeB) since it is the main producer of these light
elements at least in the early Galaxy. The O-Fe relation is crucial to the
determination of the exact physical process responsible for the LiBeB
production. Calculat... | 0011449v1 |
2001-02-27 | Variable line profiles due to non-axisymmetric patterns in an accretion disc around a rotating black hole | We have explored spectral line profiles due to spiral patterns in accretion
discs around black holes. A parametrization was employed for the shape and
emissivity of spiral waves, which can be produced by non-axisymmetric
perturbations affecting the disc density and ionization structure. The effects
of the light-travel ... | 0102460v1 |
2001-03-21 | An iterative technique for solving equations of statistical equilibrium | Superlevel partitioning is combined with a simple relaxation procedure to
construct an iterative technique for solving equations of statistical
equilibrium. In treating an $N$-level model atom, the technique avoids the
$N^{3}$ scaling in computer time for direct solutions with standard linear
equation routines and also... | 0103338v1 |
2001-03-27 | X-rays and accretion discs as probes of the strong gravity of black holes | The observations and interpretation of broad iron lines in the X-ray spectra
of Seyfert 1 galaxies are reviewed. The line profiles observed from
MCG--6-30-15 and NGC 3516 show extended red wings to the line explained by
large gravitational redshifts. The results are consistent with the emission
expected from an X-ray i... | 0103438v1 |
2001-06-13 | Non-pulsing emission from X-ray pulsars | Results of GRANAT/ART-P observations of three X-ray pulsars in non-pulsing
states are presented: 1) a statistically significant non-pulsing flux with a
simple power-law spectrum was detected during the ``off''- state of Her X-1; 2)
a significant (13 $\sigma$) non-pulsing flux with a strong iron emission line
at energie... | 0106237v1 |
2001-11-04 | Polarization of X-ray emission from the Sgr B2 cloud | The Sgr B2 giant molecular cloud is claimed to be an "X-ray reflection
nebula" - the reprocessing site of a powerful flare of the Sgr A* source,
occurred few hundred years ago. The shape of the X-ray spectrum and the
strength of the iron fluorescent line support this hypothesis. We argue that
the most clean test of the... | 0111065v1 |
2001-12-17 | Probing the Central Engine of the Narrow-Line Seyfert 1 Galaxies | The central engine of the the Narrow Line Seyfert 1 galaxies is being probed.
We use the ASCA and RXTE data to model the X-ray primary continuum as well as
the reflected component and iron $K\alpha$ line. Since these are strongly
coupled, we obtain independent measurements of the disc ionization level and
the orientati... | 0112388v1 |
2002-06-01 | On the Progenitors of Collapsars | We study the evolution of stars that may be the progenitors of common
(long-soft) GRBs. Bare rotating helium stars, presumed to have lost their
envelopes due to winds or companions, are followed from central helium ignition
to iron core collapse. Including realistic estimates of angular momentum
transport (Heger, Lange... | 0206005v1 |
2002-07-05 | Cosmic ray drift, the second knee and galactic anisotropies | We show that the second knee in the cosmic ray spectrum (i.e. the steepening
occurring at $E\simeq 4\times 10^{17}$ eV) could be related to drift effects
affecting the heaviest nuclear component, the iron group nuclei, in a scenario
in which the knee at $3\times 10^{15}$ eV indicates the onset of drift effects
in the l... | 0207143v1 |
2002-07-19 | Carbon Isotopic Abundances in the Red Giants of Omega Centauri (NGC5139) | Carbon-12 and carbon-13 abundances are measured in eleven red-giant members
of the globular cluster Omega Centauri via observations of first-overtone CO
bands near 2.3 microns. The mean value for the entire sample is <12C/13C>= 4.3
+/-0.4, with nine giants equal, within the errors, to the equilibrium ration of
12C/13C=... | 0207434v1 |
2002-07-20 | Antimatter in the Universe | Different scenarios of baryogenesis are briefly reviewed from the point of
view of possibility of generation of cosmologically interesting amount of
antimatter. It is argued that creation of antimatter is possible and natural in
many models. In some models not only anti-helium may be produced but also a
heavier anti-el... | 0207441v1 |
2002-11-12 | Line Profiles from Different Accretion Engine Geometries | Line profiles represent an important probe of the geometry and dynamics of
the central accretion engines in AGN. Although a flat disk illuminated from
above can explain the relativistic Fe K alpha line profile in some cases,
current data, plausible disk physics, and future comparison to the iron and
other AGN lines inv... | 0211236v1 |
2002-11-26 | Spectral properties of the X-ray binary pulsar LMC X-4 during different intensity states | We present spectral variations of the binary X-ray pulsar LMC X-4 observed
with the RXTE/PCA during different phases of its 30.5 day long third period.
Only out of eclipse data were used for this study. The 3-25 keV spectrum,
modeled with high energy cut-off power-law and iron line emission is found to
show strong depe... | 0211558v1 |
2003-08-29 | Iron Line Diagnostics for the GRS 1915+105 Black Hole | The properties of the broad Fe line detected in two BeppoSAX observations of
the microquasar GRS 1915+105 are summarized. | 0308539v1 |
2003-12-09 | The ionization equilibrium of iron in H II regions | We study the ionization equilibrium of Fe using photoionization models that
incorporate improved values for the ionization and recombination cross-sections
and the charge-exchange rates for the Fe ions. The previously available
photoionization models predict concentrations of Fe3+ which are a factor of 3-8
higher than ... | 0312246v1 |
2004-01-16 | Modeling AGN spectra with PHOENIX: a self-consistent approach | We find that spectra of certain Iron Low Ionization Broad Absorption Line
(FeLOBAL) QSOs, which are characterized by low--ionization emission and blue
shifted absorption lines, can be well matched with the spectral synthesis code
SYNOW. SYNOW is a resonance scattering code and assumes that line emission
comes from a si... | 0401346v1 |
2004-08-12 | Chemical analysis of 24 dusty (pre-)main-sequence stars | We have analysed the chemical photospheric composition of 24 Herbig Ae/Be and
Vega-type stars in search for the lambda Bootis phenomenon. We present the
results of the elemental abundances of the sample stars. Some of the stars were
never before studied spectroscopically at optical wavelengths. We have
determined the p... | 0408221v1 |
2004-09-10 | The L to T Dwarf Transition | While the precise mechanism responsible for the L to T dwarf transition
remains unclear, it is clearly caused by changing cloud characteristics. Here
we briefly review data relevant to understanding the nature of the transition
and argue that changing atmospheric dynamics produce the transition by opening
holes through... | 0409267v1 |
2004-10-27 | An Iron-Rich Sun and Its Source of Energy | Mass-fractionation enriches light elements and the lighter isotopes of each
element at the solar surface, making a photosphere that is 91 percent H and 9
percent He. The solar interior consists mostly of elements that comprise 99
percent of ordinary meteorites (Fe, O, Ni, Si, S, Mg and Ca) elements made in
the deep int... | 0410646v1 |
2004-11-04 | Filamentary jets as a cosmic-ray "Zevatron" | Strong, anisotropic turbulence reflecting magnetized filaments is considered,
to model the diffusive acceleration of particles by shock waves in active
galactic nucleus jets. We address that at knot A of the nearby M87 jet, the
shock involving the filamentary turbulence can accelerate an iron nucleus to
zetta-eV (ZeV; ... | 0411101v3 |
2005-01-23 | Supernova Rates in Galaxy Clusters | Measurements of SN rates in different environments and redshifts can shed
light on the nature of SN-Ia progenitors, star formation history, and chemical
enrichment history. I summarize some recent work by our group in this area, and
discuss the implications. The current evidence favors production of most of the
iron in... | 0501492v1 |
2005-02-24 | The polarized electron target as a new solar-neutrino detector | In this paper, we analyze the scattering of solar neutrinos on the polarized
electron target, and predict how the effect of parity violation in weak
interactions may help to distinguish neutrino signal from detector background.
We indicate that the knowledge of the Sun motion across the sky is sufficient
to predict the... | 0502522v1 |
2005-04-12 | ASCA and XMM-Newton Observations of A2029 | The X-ray data of A2029 obtained with XMM-Newton show no evidence of an
embedded AGN in the central region of this cluster, which was suggested from
the analysis of restored ASCA image data, although some hot spots are seen
within or around the central cD galaxy. The absence of AGN at the cluster
center is consistenten... | 0504268v1 |
2005-07-12 | Disentangling the composite continuum of symbiotic binaries I. S-type systems | We describe a method of disentangling the composite,0.12-5 microns continuum
of symbiotic binaries.The observed SED is determined by the IUE/HST archival
spectra and flux-points corresponding to the optical UBVRI and infrared JHKLM
photometric measurements. The modeled SED is given by superposition of fluxes
from the c... | 0507272v1 |
2005-09-08 | HE1327-2326, an unevolved star with [Fe/H]<-5.0. I. A Comprehensive Abundance Analysis | We present the elemental abundances of HE1327-2326, the most iron-deficient
star known, determined from a comprehensive analysis of spectra obtained with
the Subaru Telescope High Dispersion Spectrograph. | 0509206v1 |
2005-12-05 | Nonideal strongly magnetized plasmas of neutron stars and their electromagnetic radiation | We study the equation of state, polarization and radiation properties for
nonideal, strongly magnetized plasmas which compose outer envelopes of magnetic
neutron stars. Detailed calculations are performed for partially ionized
hydrogen atmospheres and for condensed hydrogen or iron surfaces of these
stars. This is a co... | 0512088v1 |
2005-12-27 | Observations of H-alpha, iron, and oxygen lines in B, Be, and shell stars | We have carried out a spectroscopic survey of several B, Be, and shell stars
in optical and near-infrared regions. Line profiles of the H-alpha line and of
selected Fe II and O I lines are presented. | 0512619v1 |
2006-05-06 | Abundances of s-process elements in planetary nebulae: Br, Kr & Xe | We identify emission lines of post-iron peak elements in very high
signal-to-noise spectra of a sample of planetary nebulae. Analysis of lines
from ions of Kr and Xe reveals enhancements in most of the PNe, in agreement
with the theories of s-process in AGB star. Surprisingly, we did not detect
lines from Br even thoug... | 0605181v1 |
2006-10-01 | HST and FUSE Spectroscopy of the DAO-type Central Star LS V+4621 | The DAO-type white dwarf LS V+4621 is the hydrogen-rich central star of the
possible planetary nebula Sh 2-216. We have taken high-resolution, high-S/N
ultraviolet spectra with STIS aboard the HST and FUSE in order to constrain its
photospheric parameters. A detailed spectral analysis by means of
state-of-the-art NLTE ... | 0610019v1 |
2006-10-07 | General Relativity effects and line emission | General Relativity effects (gravitational redshift, light bending, ...)
strongly modify the characteristics of the lines emitted close to the Black
Hole in Active Galactic Nuclei and Galactic Black Hole systems. These effects
are reviewed and illustrated, with particular emphasis on line emission from
the accretion dis... | 0610224v1 |
2006-11-16 | A Sr-Rich Star on the Main Sequence of Omega Centauri | Abundance ratios relative to iron for carbon, nitrogen, strontium and barium
are presented for a metal-rich main sequence star ([Fe/H]=--0.74) in the
globular cluster omega Centauri. This star, designated 2015448, shows depleted
carbon and solar nitrogen, but more interestingly, shows an enhanced abundance
ratio of str... | 0611509v1 |
2006-11-29 | Spectropolarimetric diagnostics of thermonuclear supernova explosions | Even at extragalactic distances, the shape of supernova ejecta can be
effectively diagnosed by spectropolarimetry. We present here results for 17
Type Ia supernovae that allow a statistical study of the correlation among the
geometric structures and other observable parameters of Type Ia supernovae.
These observations ... | 0611902v1 |
2007-03-20 | Limits on iron-dominated fallback disk in SN 1987A | The non-detection of a point source in SN1987A imposes an upper limit for the
optical luminosity of L=2L_sun. This limits the size of a possible fallback
disk around the stellar remnant. Assuming a steady-state thin disk with
blackbody emission requires a disk smaller than 100,000 km if the accretion
rate is at 30% of ... | 0703520v1 |
1995-07-07 | Nonlinear magneto-optical Kerr spectra of thin ferromagnetic iron films calculated with ab initio theory | Using a spin-polarized full-potential linear muffin-tin orbital method we
present calculations of the nonlinear magneto-optical Kerr effect for thin bcc
Fe films within a slab geometry. Film layer dependent contributions to the Kerr
spectrum are determined. Thus, we calculate the magneto-optical Kerr spectra
for the li... | 9507018v1 |
1997-03-04 | Magnetic and thermodynamic properties of Sr_{2}LaFe_{3}O_{9} | Using a Dirac-Heisenberg Hamiltonian with biquadratic exchange interactions,
we study the effect of iron disproportionation on the magnetic ordering, and
describe the first-order magnetic transition occurring in the perovskite
Sr_{2}LaFe_{3}O_{9}. Upon fitting the experimental data, we give an estimate of
the exchange ... | 9703044v1 |
1998-05-07 | The first principles calculation of transport coefficients | We demonstrate the practical feasibility of calculating transport
coefficients such as the viscosity of liquids completely from first principles
using the Green-Kubo relations. Results presented for liquid aluminum are shown
to have a statistical error of only ca. 5%. The importance of such calculations
is illustrated ... | 9805082v1 |
1999-04-29 | First- principle calculations of magnetic interactions in correlated systems | We present a novel approach to calculate the effective exchange interaction
parameters based on the realistic electronic structure of correlated magnetic
crystals in local approach with the frequency dependent self energy. The analog
of ``local force theorem'' in the density functional theory is proven for
highly corre... | 9904428v1 |
1999-08-24 | Tunable Charge Density Wave Transport in a Current-Effect Transistor | The collective charge density wave (CDW) conduction is modulated by a
transverse single-particle current in a transistor-like device. Nonequilibrium
conditions in this geometry lead to an exponential reduction of the depinning
threshold, allowing the CDWs to slide for much lower bias fields. The results
are in excellen... | 9908339v1 |
1999-08-26 | Magnons in real materials from density-functional theory | We present an implementation of the adiabatic spin-wave dynamics of Niu and
Kleinman. This technique allows to decouple the spin and charge excitations of
a many-electron system using a generalization of the adiabatic approximation.
The only input for the spin-wave equations of motion are the energies and Berry
curvatu... | 9908386v1 |
2000-11-29 | Giant Magnetoresistance at the Interface of Iron Thin Films | Ag/Fe/Ag and Cr/Fe/Cr trilayers with a single $25 nm$ thick ferromagnetic
layer exhibit giant magnetoresistance (GMR) type behavior. The resistance
decreases for parallel and transversal magnetic field alignements with a
Langevin-type magnetic field dependence up to B=12 T. The phenomenon is
explained by a granular int... | 0011491v1 |
2002-05-30 | Spin-dependent properties of a two-dimensional electron gas with ferromagnetic gates | A theoretical prediction of the spin-dependent electron self-energy and
in-plane transport of a two-dimensional electron gas in proximity with a
ferromagnetic gate is presented. The application of the predicted
spin-dependent properties is illustrated by the proposal of a device
configuration with two neighboring ferro... | 0205651v2 |
2002-07-10 | Different routes to charge disproportionation in perovskites-type Fe oxides | Iron perovskites CaFeO_3 and La_{0.33}Sr_{0.67}FeO_3 show charge
disproportionation, resulting in charge-ordered states with Fe^{3+}:Fe^{5+}
=1:1 and =2:1, respectively. We have made photoemission and unrestricted
Hartree-Fock band-structure calculation of CaFeO_3 and compared it with
La_{0.33}Sr_{0.67}FeO_3. With decr... | 0207250v1 |
2002-07-26 | Ballistic versus diffusive magnetoresistance of a magnetic point contact | The quasiclassical theory of a nanosize point contacts (PC) between two
ferromagnets is developed. The maximum available magnetoresistance values in PC
are calculated for ballistic versus diffusive transport through the area of a
contact. In the ballistic regime the magnetoresistance in excess of few
hundreds percents ... | 0207648v1 |
2002-11-01 | Exploring dynamical magnetism with time-dependent density-functional theory: from spin fluctuations to Gilbert damping | We use time-dependent spin-density-functional theory to study dynamical
magnetic phenomena. First, we recall that the local-spin-density approximation
(LSDA) fails to account correctly for magnetic fluctuations in the paramagnetic
state of iron and other itinerant ferromagnets. Next, we construct a
gradient-dependent d... | 0211021v1 |
2003-05-06 | Probing the shape of atoms in real space | The structure of single atoms in real space is investigated by scanning
tunneling microscopy. Very high resolution is possible by a dramatic reduction
of the tip-sample distance. The instabilities which are normally encountered
when using small tip-sample distances are avoided by oscillating the tip of the
scanning tun... | 0305103v1 |
2003-06-21 | The Effect of Disorder on a Quantum Phase Transition | The conductivity and magnetization of Fe1-xCoxS2 were measured to investigate
quantum critical behavior in disordered itinerant magnets. Small x (<0.001) is
required to convert insulating iron pyrite into a metal, followed by a
paramagnetic-to-ferromagnetic metal transition at x = 0.032+/-0.004. Singular
contributions ... | 0306541v1 |
2003-09-09 | Finite-Temperature Micromagnetics of Hysterisis for Misaligned Single Iron Nanopillars | We present micromagnetic results for the hysterisis of a single magnetic
nanopillar which is misaligned with respect to the applied magnetic field. We
provide results for both a one dimensional stack of magnetic rotors and of full
micromagnetic simulations. The results are compared to the Stoner-Wohlfarth
model. | 0309237v1 |
2004-01-12 | Generalized Friedel sum rule and anomalies of the mobility due to the resonant scattering of electrons by donor impurities in semiconductors | On the basis of Friedel approach the theoretical description of the effects
of resonance scattering of conduction electrons by donor impurities in
semiconductors with allowance for the stabilization of electron concentration
in coinciding the Fermi energy with the resonance level energy has been
developed. It has been ... | 0401174v1 |
2004-02-13 | Intersite elastic coupling and invar effect | The invar phenomenon (very small thermal expansion in some iron alloys or
compounds) is usually explained by the thermally-induced transitions between
different spin states of Fe, having different atomic volumes. We consider these
processes taking into account elastic interaction between Fe atoms in different
spin stat... | 0402374v1 |
2004-04-08 | Projective Dynamics in Realistic Models of Nanomagnets | The free-energy extrema governing the magnetization-reversal process for a
model of an iron nanopillar are investigated using the projective dynamics
method. Since the time evolution of the model is computationally intensive, one
could question whether sufficient statistics can be generated, with current
resources, to ... | 0404198v1 |
2004-10-06 | Spin and Valence-Fluctuation Mediated Superconductivity in Pressurized Fe and CeCu2(Si/Ge)2 | We review the evidence supporting valence-fluctuation mediated
superconductivity in CeCu2Si2 and CeCu2Ge2, where Tc reaches 2.4 K at high
pressure. In these systems the valence and magnetic critical points, at p_V and
p_c respectively, are well separated. Characteristic signatures associated with
both phenomena are dis... | 0410143v1 |
2005-01-17 | Jahn-Teller stabilization of a "polar" metal oxide surface: Fe3O4(001) | Using ab initio thermodynamics we compile a phase diagram for the surface of
Fe3O4(001) as a function of temperature and oxygen pressures. A hitherto
ignored polar termination with octahedral iron and oxygen forming a wave-like
structure along the [110]-direction is identified as the lowest energy
configuration over a ... | 0501402v1 |
2005-07-06 | Inverse Magnetoresistance of Molecular Junctions | We present calculations of spin-dependent electron transport through single
organic molecules bridging pairs of iron nanocontacts. We predict the
magnetoresistance of these systems to switch from positive to negative with
increasing applied bias for both conducting and insulating molecules. This
novel inverse magnetore... | 0507126v2 |
2005-09-09 | Correlated hybridization in transition metal complexes | We apply local orbital basis density functional theory (using SIESTA) coupled
with a mapping to the Anderson impurity model to estimate the Coulomb assisted
or correlated hybridization between transition metal d-orbitals and ligand
sp-orbitals for a number of molecular complexes. We find remarkably high values
which ca... | 0509259v4 |
2005-09-12 | Linear scaling Krylov subspace method for large scale {\it ab initio} electronic structure calculations of metals | An efficient and robust linear scaling method is presented for large scale
{\it ab initio} electronic structure calculations of a wide variety of
materials including metals. The detailed short range and the effective long
range contributions to the electronic structure are taken into account by
solving an embedded clus... | 0509291v1 |
2005-12-19 | Experimental Evidence for Crossed Andreev Reflection | We report on electronic transport properties of mesoscopic
superconductor-ferromagnet spin-valve structures. Two ferromagnetic iron leads
form planar tunnel contacts to a superconducting aluminum wire, where the
distance of the two contacts is of the order of the coherence length of the
aluminum. We observe a negative ... | 0512445v1 |
2005-12-19 | Spin injection into a short DNA chain | Quantun spin transport through a short DNA chain connected to ferromagnetic
electrodes has been investigated by the transfer matrix method. We describe the
system by a tight-binding model where the parameters are extracted from the
experimental data and realistic metal energy bands. For ferromagnetic iron
electrodes, t... | 0512473v1 |
2005-12-22 | Point defect concentrations in metastable Fe-C alloys | Point defect species and concentrations in metastable Fe-C alloys are
determined using density functional theory and a constrained free-energy
functional. Carbon interstitials dominate unless iron vacancies are in
significant excess, whereas excess carbon causes greatly enhances vacancy
concentration. Our predictions a... | 0512598v2 |
2005-12-31 | Physical nature of fcc-bcc martensitic transformation in iron based alloys | The summary of the models offered by the author revealing features of the
physical mechanisms controlling processes of martensite crystal formation is
resulted. The rapid growth of a cooling martensite crystal is considered as a
self-organized process controlled by the quasi-longitudinal lattice
displacement waves (DW)... | 0601002v1 |
2006-02-03 | Low Ghz loss in sputtered epitaxial Fe | We show that sputtered, pure epitaxial iron films can have high-frequency
loss as low as, or lower than, any known metallic ferromagnetic
heterostructure. Minimum 34 Ghz ferromagnetic resonance (FMR) linewidths of 41
Oe are demonstrated, some ~ 5-10 % lower than the previous minimum reported for
molecular beam epitaxia... | 0602094v1 |
2006-06-01 | Structure peculiarities of cementite and their influence on the magnetic characteristics | The iron carbide $Fe_3C$ is studied by the first-principle density functional
theory. It is shown that the crystal structure with the carbon disposition in a
prismatic environment has the lowest total energy and the highest energy of
magnetic anisotropy as compared to the structure with carbon in an octahedron
environm... | 0606024v1 |
2007-02-06 | Comment on Resonant X-ray diffraction studies on the charge ordering in magnetite | In a recent letter, E. Nazarenko et al [Phys. Rev. Lett. 97, 056403 (2006)
and cond-mat/0606596] have investigated the low temperature phase of magnetite
by means of resonant X-ray scattering. The paper puts forward the quantitative
determination of an effective charge ordering (CO) of 0.24 electron among the
octahedra... | 0702135v2 |
2001-02-23 | The fate of classical tensor inhomogeneities in pre-big-bang string cosmology | In pre-big-bang string cosmology one uses a phase of dilaton-driven inflation
to stretch an initial (microscopic) spatial patch to the (much larger) size of
the big-bang fireball. We show that the dilaton-driven inflationary phase does
not naturally iron out the initial classical tensor inhomogeneities unless the
initi... | 0102102v1 |
1995-08-02 | Search for Magnetic Monopoles Trapped in Matter | There have been many searches for magnetic monopoles in flight, but few for
monopoles in matter. We have searched for magnetic monopoles in meteorites,
schists, ferromanganese nodules, iron ores and other materials. The detector
was a superconducting induction coil connected to a SQUID (Superconducting
Quantum Interfer... | 9508003v1 |
1998-12-11 | The OPERA Experiment | OPERA(Oscillation Project with Emulsion-tRacking Apparatus) is a new detector
concept, iron(lead)-emulsion for a long-baseline neutrino oscillation
experiment. This experiment would perform an appearance search for nu_mu-nu_tau
oscillation in the parameter region indicated by the atmospheric neutrino
anomaly. OPERA can... | 9812015v3 |
1999-03-22 | Study of the Hadron Shower Profiles with the Tile Hadron Calorimeter | The lateral and longitudinal profiles of the hadronic showers detected by
iron-scintillator tile hadron calorimeter with longitudinal tile configuration
have been investigated. The results are based on 100 GeV pion beam data. Due to
the beam scan provided many different beam impact locations with cells it is
succeeded ... | 9903052v1 |
1999-08-20 | Precision Calibration of the NuTeV Calorimeter | NuTeV is a neutrino-nucleon deep-inelastic scattering experiment at Fermilab.
The detector consists of an iron-scintillator sampling calorimeter interspersed
with drift chambers, followed by a muon toroidal spectrometer. We present
determinations of response and resolution functions of the NuTeV calorimeter
for electro... | 9908056v1 |
1999-12-23 | Recent atmospheric neutrino results from Soudan 2 | An updated measurement of the atmospheric nu_mu/nu_e ratio-of-ratios,
0.68+-0.11+-0.06, has been obtained using a 4.6-kty exposure of the Soudan-2
iron tracking calorimeter. The L/E distributions have been analyzed for effects
of nu_mu -> nu_x oscillations, and an allowed region in the Delta m^2 vs. sin^2
2 theta plane... | 9912060v1 |
2001-09-18 | Nuclear transparency from quasielastic A(e,e'p) reactions uo to Q^2=8.1 (GeV/c)^2 | The quasielastic (e,e$^\prime$p) reaction was studied on targets of
deuterium, carbon, and iron up to a value of momentum transfer $Q^2$ of 8.1
(GeV/c)$^2$. A nuclear transparency was determined by comparing the data to
calculations in the Plane-Wave Impulse Approximation. The dependence of the
nuclear transparency on ... | 0109027v1 |
2002-01-10 | A method for detecting $ν_τ$ appearance in the spectra of quasielastic CC events | A method for detecting the transition \omutau in long-baseline accelerator
experiments, that consists in comparing the far-to-near ratios of the spectra
of quasielastic CC events generated by high- and low-energy beams of muon
neutrinos, is proposed. The test may be accessible to big water Cherenkov
detectors and iron-... | 0201019v1 |
2003-07-02 | NuTeV Cross Section and Structure Function Measurements | The NuTeV experiment has obtained a unique high statistics sample of neutrino
and antineutrino interactions using its high-energy sign-selected beam.
Charged-current neutrino and anti-neutrino differential cross sections are
extracted. Neutrino-Iron structure functions, F_2(x,Q^2) and xF_3(x,Q^2), are
determined by fit... | 0307005v2 |
2005-07-02 | The MINOS Detectors | The Main Injector Neutrino Oscillation Search (MINOS) experiment's primary
goal is the precision measurement of the neutrino oscillation parameters in the
atmospheric neutrino sector. This long-baseline experiment uses Fermilab's NuMI
beam, measured with a Near Detector at Fermilab, and again 735 km later using a
Far D... | 0507018v1 |
2005-07-09 | NuTeV Structure Function Measurement | The NuTeV experiment obtained high statistics samples of neutrino and
anti-neutrino charged current events during the 1996-1997 Fermilab fixed target
run. The experiment combines sign-selected neutrino and anti-neutrino beams and
the upgraded CCFR iron-scintillator neutrino detector. A precision continuous
calibration ... | 0507040v1 |
1996-07-10 | QCD analysis of the CCFR data for $xF_3$ and Higher--Twist Contribution | The QCD analysis of the $xF_3$ structure function measured in deep-inelastic
scattering of neutrinos and antineutrinos on an iron target at the Fermilab
Tevatron is done in 1--, 2-- and 3--loop order of QCD. The x dependence of the
higher--twist contribution is evaluated. The experimental value of
higher--twist correct... | 9607275v2 |
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