5,581 research outputs found
Inclusive quasi-elastic electron-nucleus scattering
This article presents a review of the field of inclusive quasi-elastic
electron-nucleus scattering. It discusses the approach used to measure the data
and includes a compilation of data available in numerical form. The theoretical
approaches used to interpret the data are presented. A number of results
obtained from the comparison between experiment and calculation are then
reviewed. The analogies and differences to other fields of physics exploiting
quasi-elastic scattering from composite systems are pointed out.Comment: Accepted for publication in Reviews of Modern Physic
Resonant photoemission at the absorption edge of Mn and Ti and electronic structure of 1T-MnTiSe
Resonant valence-band X-ray photoelectron spectra (ResPES) excited near
2p core level energies, 2p X-ray photoelectron spectra (XPS) and
L X-ray absorption spectra (XAS) of Ti and Mn in single crystal of
1T-MnTiSe were studied for the first time. The ionic-covalent character
of bonds formed by Mn atoms with the neighboring Se atoms in the octahedral
coordination is established. From the XPS and XAS measurements compared with
results of atomic multiplet calculations of Ti and Mn L XAS it is found
that Ti atoms are in ionic state of 4+ and Mn atoms are in the state of 2+. In
ResPES of MnTiSe excited near Ti 2p and Mn 2p
absorption edges the Ti 3d and Mn 3d bands at binding energies just below the
Fermi level are observed. According to band structure calculations
E the Ti 3d states are localized in the vicinity of
point and the Mn 3d states are localized along the direction
K--M in the Brillouin zone of the crystal.Comment: 18 pages (preprint), 9 figure
Synthesis of Decorated Carbon Structures with Encapsulated Components by Low-Voltage Electric Discharge Treatment
Abstract: Polycondensation of complexes of chloromethanes with triphenylphosphine by the action of low-voltage electric discharges in the liquid phase gives nanosized solid products. The elemental composition involving the generation of element distribution maps (scanning electron microscopy–energy dispersive X‑ray spectroscopy mapping) and the component composition (by direct evolved gas analysis–mass spectrometry) of the solid products have been studied. The elemental and component compositions of the result-ing structures vary widely depending on the chlorine content in the substrate and on the amount of triphenylphosphine taken. Thermal desorption analysis revealed abnormal behavior of HCl and benzene present in the solid products. In thermal desorption spectra, these components appear at an uncharacteristically high temperature. The observed anomaly in the behavior of HCl is due to HCl binding into a complex of the solid anion HCI-2 with triphenyl(chloromethyl)phosphonium chloride, which requires a relatively high temperature (up to 800 K) to decompose. The abnormal behavior of benzene is associated with its encapsulated state in nanostructures. The appearance of benzene begins at 650 K and continues up to temperatures above 1300 K. © 2022, The Author(s).The work was carried out with the equipment of the "Modern Nanotechnologies" Ural Shared-Use Center at the Ural Federal University. The study was supported by the Russian Foundation for Basic Research, project no. 18-29-24008
On the critical level-curvature distribution
The parametric motion of energy levels for non-interacting electrons at the
Anderson localization critical point is studied by computing the energy
level-curvatures for a quasiperiodic ring with twisted boundary conditions. We
find a critical distribution which has the universal random matrix theory form
for large level-curvatures corresponding to
quantum diffusion, although overall it is close to approximate log-normal
statistics corresponding to localization. The obtained hybrid distribution
resembles the critical distribution of the disordered Anderson model and makes
a connection to recent experimental data.Comment: 4 pages, 3 figure
Andreev levels in a single-channel conductor
We calculate the subgap density of states of a disordered single-channel
normal metal connected to a superconductor at one end (NS junction) or at both
ends (SNS junction). The probability distribution of the energy of a bound
state (Andreev level) is broadened by disorder. In the SNS case the two-fold
degeneracy of the Andreev levels is removed by disorder leading to a splitting
in addition to the broadening. The distribution of the splitting is given
precisely by Wigner's surmise from random-matrix theory. For strong disorder
the mean density of states is largely unaffected by the proximity to the
superconductor, because of localization, except in a narrow energy region near
the Fermi level, where the density of states is suppressed with a log-normal
tail.Comment: 12 pages, 5 figure
Dispersive wave runup on non-uniform shores
Historically the finite volume methods have been developed for the numerical
integration of conservation laws. In this study we present some recent results
on the application of such schemes to dispersive PDEs. Namely, we solve
numerically a representative of Boussinesq type equations in view of important
applications to the coastal hydrodynamics. Numerical results of the runup of a
moderate wave onto a non-uniform beach are presented along with great lines of
the employed numerical method (see D. Dutykh et al. (2011) for more details).Comment: 8 pages, 6 figures, 18 references. This preprint is submitted to
FVCA6 conference proceedings. Other author papers can be downloaded at
http://www.lama.univ-savoie.fr/~dutykh
Spin-transfer torque effects in the dynamic forced response of the magnetization of nanoscale ferromagnets in superimposed ac and dc bias fields in the presence of thermal agitation
Spin-transfer torque (STT) effects on the stationary forced response of
nanoscale ferromagnets subject to thermal fluctuations and driven by an ac
magnetic field of arbitrary strength and direction are investigated via a
generic nanopillar model of a spin-torque device comprising two ferromagnetic
strata representing the free and fixed layers and a nonmagnetic conducting
spacer all sandwiched between two ohmic contacts. The STT effects are treated
via the Brown magnetic Langevin equation generalized to include the Slonczewski
STT term thereby extending the statistical moment method [Y. P. Kalmykov et
al., Phys. Rev. B 88, 144406 (2013)] to the forced response of the most general
version of the nanopillar model. The dynamic susceptibility, nonlinear
frequency-dependent dc magnetization, dynamic magnetic hysteresis loops, etc.
are then evaluated highlighting STT effects on both the low-frequency thermal
relaxation processes and the high-frequency ferromagnetic resonance, etc.,
demonstrating a pronounced dependence of these on the spin polarization current
and facilitating interpretation of STT experiments
Graphene-based modulation-doped superlattice structures
The electronic transport properties of graphene-based superlattice structures
are investigated. A graphene-based modulation-doped superlattice structure
geometry is proposed and consist of periodically arranged alternate layers:
InAs/graphene/GaAs/graphene/GaSb. Undoped graphene/GaAs/graphene structure
displays relatively high conductance and enhanced mobilities at elevated
temperatures unlike modulation-doped superlattice structure more steady and
less sensitive to temperature and robust electrical tunable control on the
screening length scale. Thermionic current density exhibits enhanced behaviour
due to presence of metallic (graphene) mono-layers in superlattice structure.
The proposed superlattice structure might become of great use for new types of
wide-band energy gap quantum devices.Comment: 5 figure
Spatial distribution of local currents of massless Dirac fermions in quantum transport through graphene nanoribbons
We employ the formalism of bond currents, expressed in terms of the
nonequilibrium Green functions, to image the charge flow between two sites of
the honeycomb lattice of graphene ribbons of few nanometers width. In sharp
contrast to nonrelativistic electrons, current density profiles of quantum
transport at energies close to the Dirac point in clean zigzag graphene
nanoribbons (ZGNR) differs markedly from the profiles of charge density peaked
at the edges due to zero-energy localized edge states. For transport through
the lowest propagating mode induced by these edge states, edge vacancies do not
affect current density peaked in the center of ZGNR. The long-range potential
of a single impurity acts to reduce local current around it while concurrently
increasing the current density along the zigzag edge, so that ZGNR conductance
remains perfect .Comment: 5 pages, 5 figure
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