219 research outputs found
Multiple magnon modes in the CoSnS Weyl semimetal candidate
We experimentally investigate electron transport in kagome-lattice
ferromagnet CoSnS, which is regarded as a time-reversal symmetry
broken Weyl semimetal candidate. We demonstrate curves with
pronounced asymmetric spikes, similar to those attributed to
current-induced spin-wave excitations in ferromagnetic multilayers. In contrast
to multilayers, we observe several spikes' sequences at low,
10 A/cm, current densities for a thick single-crystal
CoSnS flake in the regime of fully spin-polarized bulk. The spikes
at low current densities can be attributed to novel magnon branches in magnetic
Weyl semimetals, which are predicted due to the coupling between two magnetic
moments mediated by Weyl fermions. Presence of spin-transfer effects at low
current densities in CoSnS makes the material attractive for
applications in spintronics.Comment: final versio
Heating and Cooling of Hot Accretion Flows by Non Local Radiation
We consider non-local effects which arise when radiation emitted at one
radius of an accretion disk either heats or cools gas at other radii through
Compton scattering. We discuss three situations:
1. Radiation from the inner regions of an advection-dominated flow Compton
cooling gas at intermediate radii and Compton heating gas at large radii.
2. Soft radiation from an outer thin accretion disk Compton cooling a hot
one- or two-temperature flow on the inside.
3. Soft radiation from an inner thin accretion disk Compton cooling hot gas
in a surrounding one-temperature flow.
We describe how previous results are modified by these non-local
interactions. We find that Compton heating or cooling of the gas by the
radiation emitted in the inner regions of a hot flow is not important.
Likewise, Compton cooling by the soft photons from an outer thin disk is
negligible when the transition from a cold to a hot flow occurs at a radius
greater than some minimum . However, if the hot flow terminates at
, non-local cooling is so strong that the hot gas is cooled to
a thin disk configuration in a runaway process. In the case of a thin disk
surrounded by a hot one-temperature flow, we find that Compton cooling by soft
radiation dominates over local cooling in the hot gas for \dot{M} \gsim
10^{-3} \alpha \dot{M}_{Edd}, and R \lsim 10^4 R_{Schw}. As a result, the
maximum accretion rate for which an advection-dominated one-temperature
solution exists, decreases by a factor of , compared to the value
computed under an assumption of local energy balance.Comment: LaTeX aaspp.sty, 25 pages, and 6 figures; to appear in Ap
Development of shelf ecosystems in conditions of glacioeustatic fluctuations of the ocean level
As a result of sea level change, the largest changes are observed in coastal ecosystems. One possible reason for the currently observed changes of the Black sea level is glacioeustatic fluctuations in Global sea level. In the paper, the differential equation describing changes in the relief of the shelf during the glacio–eustatic oscillations of the World Ocean level was proposed for the first time. The relationship between the inclinations of the existing and emerging shelf, abrasion rates and sea level changes is the basis of this equation. Examples of numerical and analytical solutions of the equation describing the shelf profile after the transgressive stage are given
The MRO-accompanied modes of Re-implantation into SiO2-host matrix: XPS and DFT based scenarios
The following scenarios of Re-embedding into SiO2-host by pulsed
Re-implantation were derived and discussed after XPS-and-DFT electronic
structure qualification: (i) low Re-impurity concentration mode -> the
formation of combined substitutional and interstitial impurities with
Re2O7-like atomic and electronic structures in the vicinity of oxygen
vacancies; (ii) high Re-impurity concentration mode -> the fabrication of
interstitial Re-metal clusters with the accompanied formation of ReO2-like
atomic structures and (iii) an intermediate transient mode with Re-impurity
concentration increase, when the precursors of interstitial defect clusters are
appeared and growing in the host-matrix structure occur. An amplification
regime of Re-metal contribution majority to the final Valence Band structure
was found as one of the sequences of intermediate transient mode. It was shown
that most of the qualified and discussed modes were accompanied by the MRO
(middle range ordering) distortions in the initial oxygen subnetwork of the
a-SiO2 host-matrix because of the appeared mixed defect configurations.Comment: 19 pages, 7 figures, accepted to J. Alloys and Compound
The distribution density of square value probabilities functionality from trajectories of wiener process
In the article authors develop an approach to calculating the statistic development probability for composite functions of square values in Gaussian casual process trajectories. Calculating distribution density for additive composite functions is based on standard Wiener process trajectories. Authors have developed a density formula for uniformly convergent decomposition, with x = 0. The convergence is exponentially fas
Vertical Structure of the Outer Accretion Disk in Persistent Low-Mass X-Ray Binaries
We have investigated the influence of X-ray irradiation on the vertical
structure of the outer accretion disk in low-mass X-ray binaries by performing
a self-consistent calculation of the vertical structure and X-ray radiation
transfer in the disk. Penetrating deep into the disk, the field of scattered
X-ray photons with energy \,keV exerts a significant influence on
the vertical structure of the accretion disk at a distance
\,cm from the neutron star. At a distance \,cm,
where the total surface density in the disk reaches
\,g\,cm, X-ray heating affects all layers of an
optically thick disk. The X-ray heating effect is enhanced significantly in the
presence of an extended atmospheric layer with a temperature
\,K above the accretion disk. We have derived
simple analytic formulas for the disk heating by scattered X-ray photons using
an approximate solution of the transfer equation by the Sobolev method. This
approximation has a \,% accuracy in the range of X-ray photon
energies \,keV.Comment: 19 pages, 8 figures, published in Astronomy Letter
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