66 research outputs found
Solid-state memcapacitive system with negative and diverging capacitance
We suggest a possible realization of a solid-state memory capacitive
(memcapacitive) system. Our approach relies on the slow polarization rate of a
medium between plates of a regular capacitor. To achieve this goal, we consider
a multi-layer structure embedded in a capacitor. The multi-layer structure is
formed by metallic layers separated by an insulator so that non-linear
electronic transport (tunneling) between the layers can occur. The suggested
memcapacitor shows hysteretic charge-voltage and capacitance-voltage curves,
and both negative and diverging capacitance within certain ranges of the field.
This proposal can be easily realized experimentally, and indicates the
possibility of information storage in memcapacitive devices
Electrode processes during the electrorefiniment of lead in the KCl-PbCl2-PbO melt
The influence of PbO addition on current efficiency during the electrorefinement of lead in the KCl-PbCl2-PbO melt was investigated. It was shown that with PbO concentration in the KCl-PbCl2 eqiumolar mixture increasing, the current efficiency of lead decreases. Electrode processes mechanism is proposed
Nuclear-spin qubits interaction in mesoscopic wires and rings
Theoretical study of the indirect coupling of nuclear spins (qubits) embedded
into a mesoscopic ring and in a finite length quantum wire in a magnetic field
is presented. It is found that the hyperfine interaction, via the conduction
electrons, between nuclear spins exhibits sharp maxima as function of the
magnetic field and nuclear spin positions. This phenomenon can be used for
manipulation of qubits with almost atomic precision. Experimental feasibility
and implications for quantum logics devices is discussed.Comment: 3 figures, 12 page
Research of oxygen-conducting ceramic materials for lithium chloride melt in reactors for pyrochemical processing of spent nuclear fuel
The behavior of potential ceramic materials (electrolytes conducting on oxygen ions) of electrochemical control devices of technological operations in oxide-halide melts was investigated. Based on the literature data and thermodynamic estimates for long-term tests in the LiCl, LiCl-Li2O and LiCl-Li2O-Li melts at a temperature of 650 ° C, mixtures of oxides ZrO2- Y2O3(YSZ), ZrO2-Sc2O3(ScSZ), ZrO2-CaO (CaSZ) and CeO2-Gd2O3(CGO) were selected. These melt under the studies are the most widely used in a number of high-temperature electrochemical processes of obtaining metals and alloys, as well as in the developed schemes of pyrochemical processing of nuclear fuel. The stability of the samples was determined by changes in mass, appearance, elemental analysis of the melt, as well as via the scanning electron microscopy. The best stability in LiCl-Li2O melts was shown by the samples of ZrO2-Y2O3with cubic and tetragonal structures and the samples of ZrO2-CaO. Based on the changes in the microstructure of the samples, it was concluded that the increase in the content of Li2O in the LiCl-Li2O melt accelerates the destruction of the sample mainly by the mechanism of dyeing, and the presence of lithium leads to loosening of the samples. © 2020 Institute of Physics Publishing. All rights reserved
Electronic transport through nuclear-spin-polarization-induced quantum wire
Electron transport in a new low-dimensional structure - the nuclear spin
polarization induced quantum wire (NSPI QW) is theoretically studied. In the
proposed system the local nuclear spin polarization creates the effective
hyperfine field which confines the electrons with the spins opposite to the
hyperfine field to the regions of maximal nuclear spin polarization. The
influence of the nuclear spin relaxation and diffusion on the electron energy
spectrum and on the conductance of the quantum wire is calculated and the
experimental feasibility is discussed.Comment: 5 pages, 4 figure
Drift-diffusion model for spin-polarized transport in a non-degenerate 2DEG controlled by a spin-orbit interaction
We apply the Wigner function formalism to derive drift-diffusion transport
equations for spin-polarized electrons in a III-V semiconductor single quantum
well. Electron spin dynamics is controlled by the linear in momentum spin-orbit
interaction. In a studied transport regime an electron momentum scattering rate
is appreciably faster than spin dynamics. A set of transport equations is
defined in terms of a particle density, spin density, and respective fluxes.
The developed model allows studying of coherent dynamics of a non-equilibrium
spin polarization. As an example, we consider a stationary transport regime for
a heterostructure grown along the (0, 0, 1) crystallographic direction. Due to
the interplay of the Rashba and Dresselhaus spin-orbit terms spin dynamics
strongly depends on a transport direction. The model is consistent with results
of pulse-probe measurement of spin coherence in strained semiconductor layers.
It can be useful for studying properties of spin-polarized transport and
modeling of spintronic devices operating in the diffusive transport regime.Comment: 16 pages, 3 figure
Slow Spin Relaxation in Two-Dimensional Electron Systems with Antidots
We report a Monte Carlo investigation of the effect of a lattice of antidots
on spin relaxation in twodimensional electron systems. The spin relaxation time
is calculated as a function of geometrical parameters describing the antidot
lattice, namely, the antidot radius and the distance between their centers. It
is shown that spin polarization relaxation can be efficiently suppressed by the
chaotic spatial motion due to the antidot lattice. This phenomenon offers a new
approach to spin coherence manipulation in spintronics devices.Comment: submitted to Phys. Rev.
СКОРОСТЬ РАСТВОРЕНИЯ ОКСИДА СВИНЦА (II) В ЭКВИМОЛЬНОМ РАСПЛАВЕ KCl–PbCl2
Lead (II) oxide dissolution rates in equimolar KCl–PbCl2 melt at Т = 773, 823 & 873 K have been determined by gravimetrical method. In temperature rising from 773 to 873 K, the initial dissolution rate is shown to increase from 23,9 to 45,6 mg/(cm2·min) at the conditional factor of roughness equal to 10. Then the rate values for all temperatures are lined up and after 25 min they are close to zero, thus meaning the diffusion mode of the process at the natural convection conditions. The activation energy of PbO interaction with KCl–PbCl2 melt is 37,370±0,118 kJ/mol. The PbO limiting concentration in equimolar KCl–PbCl2 melt at temperatures 773, 823 and 873 K is 9,1; 10,6; 13,5 wt.% respectively. С помощью гравиметрического метода экспериментально определены скорости растворения (W) оксида свинца (II) в эквимолярном расплаве KCl–PbCl2 при Т = 773, 823 и 873 К. Показано, что с повышением температуры с 773 до 873 К на- чальная величина W возрастает с 23,9 до 45,6 мг/(см2·мин) при условном коэффициенте шероховатости, равном 10. Далее значения W для всех температур выравниваются и после 25 мин близки к нулю, что говорит о диффузионном режиме про- цесса в условиях естественной конвекции. Энергия активации процесса взаимодействия PbO c расплавом KCl–PbCl2 составила 37,370±0,118 кДж/моль. Определена предельная концентрация PbO в эквимолярном расплаве KCl–PbCl2, ко- торая при Т = 773, 823 и 873 К соответственно равна 9,1, 10,6 и 13,5 мас.%
Spintronics: Fundamentals and applications
Spintronics, or spin electronics, involves the study of active control and
manipulation of spin degrees of freedom in solid-state systems. This article
reviews the current status of this subject, including both recent advances and
well-established results. The primary focus is on the basic physical principles
underlying the generation of carrier spin polarization, spin dynamics, and
spin-polarized transport in semiconductors and metals. Spin transport differs
from charge transport in that spin is a nonconserved quantity in solids due to
spin-orbit and hyperfine coupling. The authors discuss in detail spin
decoherence mechanisms in metals and semiconductors. Various theories of spin
injection and spin-polarized transport are applied to hybrid structures
relevant to spin-based devices and fundamental studies of materials properties.
Experimental work is reviewed with the emphasis on projected applications, in
which external electric and magnetic fields and illumination by light will be
used to control spin and charge dynamics to create new functionalities not
feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes
from the published versio
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