共查询到20条相似文献,搜索用时 46 毫秒
1.
L. V. Lubyako E. V. Suvorov A. B. Burov A. M. Shtanyuk Yu. A. Dryagin L. M. Kukin N. K. Skalyga 《Technical Physics》1998,43(8):926-933
The design and arrangement of a detection system for measuring spectra, using a 140 GHz gyrotron as the probe-radiation source,
developed for investigating collective Thomson scattering in plasma are discussed. The measurement procedure and examples
of the results obtained are presented.
Zh. Tekh. Fiz. 68, 54–62 (August 1998) 相似文献
2.
V. E. Bisti 《JETP Letters》1999,69(8):584-588
The spectrum of intersubband collective excitations of spin and charge density in a system of quasi-two-dimensional electrons
is calculated in the strong magnetic field limit for filling factors υ≤4. For υ≤2 two new closely spaced modes of collective excitations are obtained. The modes obtained make it possible to give a new
interpretation of the experimentally observed line, which is usually interpreted as being due to single-particle excitations.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 8, 543–547 (25 April 1999) 相似文献
3.
A. A. Valuev A. S. Kaklyugin G. É. Norman 《Journal of Experimental and Theoretical Physics》1998,86(3):480-488
This paper shows how the concepts commonly used for a Debye plasma—Landau damping, collisional damping, short-range and long-range
collisions, and plasma waves—must be revised to describe a nonideal electron-ion plasma. The degrees of freedom of a nonideal
plasma are divided into collective and individual. The increase and saturation of the fraction of collective degrees of freedom
as the coupling constant increases is discussed. The Tatarskii approach for a system of coupled oscillators makes it possible
to model the collective degrees of freedom of a nonideal plasma by a set of Langevin oscillators in a thermostat. The correlation
energy and the energy of the plasma waves are found. The concepts developed here made it possible to determine the dispersion
of the plasma waves and their damping. The effect of damping on the discrepancy between the position of the maximum of the
dynamic structure factor and the real part of the solution of the dispersion equation is considered. The effective collision
frequency of the individual degrees of freedom (the electrons) is estimated, taking into account both short-range pairwise
scattering and scattering at plasma waves.
Zh. éksp. Teor. Fiz. 113, 880–896 (March 1998) 相似文献
4.
A. N. Artemov 《JETP Letters》1998,68(6):492-497
The magnetization curves of a thin superconducting monolayer are calculated. It is found that for sufficiently high fields
and temperatures the magnetization of a monolayer exhibits the same features as the reversible magnetization of layered superconductors
in high fields. It is shown that these features are due to instability with respect to the dissociation of pairs of Pearl
vortices into a gas of free vortices and to collective effects in a system of free vortices.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 6, 460–465 (25 September 1998) 相似文献
5.
An expression is obtained for the electron-atom collision integral for axisymmetric low-temperature plasmas. The Legendre
components of the collision integral are determined experimentally by the probe method. Comparison of the measured Legendre
components with their theoretical values shows that, depending on the plasma conditions, the collisional regime or a regime
of dominant collective interactions is established in the system.
Zh. Tekh. Fiz. 67, 19–24 (April 1997) 相似文献
6.
We show that the propagation of short pulses in optical lines with strong dispersion management is described by an integrable
Hamiltonian system. The leading nonlinear effect is the formation of a collective dispersion which is a result of the interaction
of all pulses propagating along the line.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 9, 573–576 (10 November 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
7.
V. B. Kopeliovich 《Journal of Experimental and Theoretical Physics》1997,85(6):1060-1069
Semiclassical quantization of the SU(3)-skyrmion zero modes is performed by means of the collective coordinate method. The quantization condition known for SU(2) solitons quantized with SU(3) collective coordinates is generalized for SU(3) skyrmions with strangeness content different from zero. The quantization of the dipole-type configuration with large strangeness
content found recently is considered as an example and the spectrum and the mass splittings of the quantized states are estimated.
The energy and baryon number density of SU(3) skyrmions are presented in a form emphasizing their symmetry in different SU(2) subgroups of SU(3), and a lower bound for the static energy of SU(3) skyrmions is derived.
Zh. éksp. Teor. Fiz. 112, 1941–1958 (December 1997)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
8.
V. D. Kagan 《Physics of the Solid State》1998,40(1):112-113
At low temperatures, heat propagates in crystals in the form of collective excitations—second-sound waves. How the parameters
of the phonon system of the crystal can be determined from the shape of the heat pulse is considered here.
Fiz. Tverd. Tela (St. Petersburg) 40, 126–127 (January 1998) 相似文献
9.
This paper discusses a model of the adhesive interaction of metals and semiconductors, based on a dielectric formalism and
using the concepts of collective excitations — plasmons of the electron-ion system. Expressions are obtained in terms of the
jellium model in the longwavelength approximation for the adhesion energy and the adhesive interaction force and are determined
via the dispersion dependences of the energies of surface plasma oscillations for various materials whose surfaces are separated
by a gap of arbitrary magnitude. The adhesion energies and the adhesive interaction forces are calculated for a number of
simple and transition metals and semiconductors, and the adhesion characteristics are also obtained for the contact of the
given materials with an insulating medium.
Fiz. Tverd. Tela (St. Petersburg) 39, 964–967 (June 1997) 相似文献
10.
E. A. Zubova L. I. Manevich N. K. Balabaev 《Journal of Experimental and Theoretical Physics》1999,88(3):586-589
A molecular-dynamics model of the behavior of a vacancy in the chain of an equilibrium polymer crystal (the “collective atom”
approximation for polyethylene) is developed for the first time. It is shown that a defect of this type in a polymer crystal
has a soliton mobility, as opposed to vacancies in crystals of low-molecular substances.
Zh. éksp. Teor. Fiz. 115, 1063–1069 (March 1999) 相似文献
11.
A. É. Filippov 《Physics of the Solid State》1998,40(9):1546-1549
The molecular dynamics method is used to examine the ordering of interacting subsystems in a two-component, two-dimensional
Coulomb gas, consisting of equal amounts of positively and negatively charged particles, which simulates the behavior of a
system of interacting vortices. In particular, it is found that when the system temperature is lowered from the Kosterlitz-Thouless
transition point, additional ordering of the vortex chains may take place. It is noted that this process may stimulate the
development of vortex chains observed in real superfluid, magnetic, and superconducting systems. Possible applications of
the molecular dynamics method to phase separation and the ordering of adiabatically slowly moving subsystems in the collective
field of a fast subsystem are considered.
Fiz. Tverd. Tela (St. Petersburg) 40, 1701–1704 (September 1998) 相似文献
12.
The high-frequency excitations of the molecular insulator C60 are investigated theoretically. The model of a quantum well rolled into a sphere is used to calculate the dipole (multipole
in the general case) modes of an individual C60 cluster. If the spectrum and oscillator strengths of the collective modes of an individual cluster are known, the microscopic
continuum approach can be used to calculate the spectrum of delocalized excitations in a cluster crystal. Then the ordinary
dielectric constant formalism permits calculation of the optical characteristics of the material in the vacuum ultraviolet
region studied.
Fiz. Tverd. Tela (St. Petersburg) 40, 913–915 (May 1998) 相似文献
13.
Direct modeling of the dynamics of a system of many Coulomb particles is applied to analyze the formation stage of a metastable
plasma state from an initial, highly nonideal state, and also to consider some properties of this metastable supercooled state.
It is shown that relaxation of the average particle kinetic energy may be characterized by a universal dimensionless function
and in particular, there is a limiting degree of plasma nonideality which may be achieved in the metastable state, in the
absence of any external influence. The calculated pair correlation functions agree with the results of the Debye model, even
outside its limits of validity. The time dependence of the total dipole moment of the particle system is investigated. It
is shown that oscillations of the total dipole moment are observed. These collective oscillations take place at a frequency
slightly below the Langmuir frequency and the oscillations of free and bound electrons are in antiphase. The hypothesis is
put forward that recombination relaxation is frozen as a result of interaction between quasibound electrons and Langmuir oscillations
of free electrons.
Zh. Tekh. Fiz. 67, 42–52 (August 1997) 相似文献
14.
Using the axially-symmetric time-dependent Gross-Pitaevskii equation we study the phase coherence in a repulsive Bose-Einstein condensate (BEC) trapped by a harmonic and an one-dimensional optical lattice potential to describe the experiment by Cataliotti et al. on atomic Josephson oscillation [Science 293, 843 (2001)]. The phase coherence is maintained after the BEC is set into oscillation by a small displacement of the magnetic trap along the optical lattice. The phase coherence in the presence of oscillating neutral current across an array of Josephson junctions manifests in an interference pattern formed upon free expansion of the BEC. The numerical response of the system to a large displacement of the magnetic trap is a classical transition from a coherent superfluid to an insulator regime and a subsequent destruction of the interference pattern in agreement with the more recent experiment by Cataliotti et al. [New J. Phys. 5, 71 (2003)].Received: 20 March 2003, Published online: 30 July 2003PACS:
03.75.-b Matter waves - 03.75.Lm Tunneling, Josephson effect, Bose-Einstein condensates in periodic potentials, solitons, vortices and topological excitations - 03.75.Kk Dynamic properties of condensates; collective and hydrodynamic excitations, superfluid flow 相似文献
15.
S. V. Tarasenko 《JETP Letters》1996,63(4):247-251
The necessary conditions under which the phonon and electron mechanisms of interlayer exchange combine to form new types of
both surface and volume collective spin-wave excitations in a magnetic superstructure of the magnet-nonmagnetic-metal type
are given. As an example, a new type of doubly-partial generalized surface spin wave and a new type of inhomogeneous spin-spin
resonance are found for superlattices of the antiferromagnet-nonmagnetic-metal type.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 4, 232–236 (25 February 1996) 相似文献
16.
A. I. Tartakovskii V. D. Kulakovskii Yu. I. Koval’ T. B. Borzenko A. Forchel J. P. Reithmaier 《Journal of Experimental and Theoretical Physics》1998,87(4):723-730
The structure of the photon states and dispersion of cavity polaritons in semiconductor microcavities with two-dimensional
optical confinement (photon wires), fabricated from planar Bragg structures with a quantum well in the active layer, are investigated
by measuring the angular dependence of the photoluminescence spectra. The size quantization of light due to the wavelength-commensurate
lateral dimension of the cavity causes additional photon modes to appear. The dispersion of polaritons in photon wires is
found to agree qualitatively with the prediction for wires having an ideal quantum well, for which the spectrum is formed
by pairwise interaction between exciton and photon modes of like spatial symmetry. The weak influence of the exciton symmetry-breaking
random potential in the quantum well indicates a mechanism of polariton production through light-induced collective exciton
states. This phenomenon is possible because the light wavelength is large in comparison with the exciton radius and the dephasing
time of the collective exciton state is long.
Zh. éksp. Teor. Fiz. 114, 1329–1345 (October 1998) 相似文献
17.
Vassilios Fessatidis Norman J.M. Horing 《Physica E: Low-dimensional Systems and Nanostructures》2005,27(4):487-494
We examine the collective mode spectrum for a double quantum-wire system embedded in semi-infinite polar medium, taking account of the role of optical phonons in interaction with the double quantum-wire plasmons and bulk/surface plasmons. The collective mode frequencies are exhibited as functions of qx (wavenumber parallel to the wires) and as functions of z0 (distance of first wire from the interface). We also find that the region of drift instability of the collective modes is split into two disjoint regions of instability by the optical phonons, with a region of stability between them. 相似文献
18.
H.A. Radovan H.H. Wen P. Ziemann 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(4):533-540
Using a specially designed SQUID magnetometer we measured the temperature dependence of the critical current density in a
ring patterned thin film for magnetic fields parallel to the c-axis. In addition, the temporal relaxation of the remanent state as prepared by field cooling in an external field of 100
Oe at different temperatures is determined. The j
c
(
T
) data show a field-dependent anomalous kink close to Tc pointing to reduced dissipation with increasing temperature allowing to construct a corresponding H-T borderline. A similar behavior is observed for the normalized relaxation rate S
(
T
) as extracted from the temporal behavior of the remanent state, which, at low temperatures, exhibits the expected increase
for increasing T-values, while an anomalous decrease of S
(
T
) is found for temperatures above 85 K. While the low-T regime is attributed to creep of 2D pinned single vortex lines, the high-T behavior is suggested to be dominated by collective motion with a more sluggish dynamics. This change in dynamics is also
reflected by the activation barriers for flux creep U
(
j
), which show a corresponding crossover in μ from 0.06 to 0.99. An additional scaling analysis of the E-j characteristics for according to vortex glass theory reveals quasi-2D collective creep behavior with .
Received: 8 April 1998 / Revised: 15 July 1998 / Accepted: 2 September 1998 相似文献
19.
Collective oscillations in thermal equilibrium are shown to represent only a small fraction of the degrees of freedom of a liquid metal, the important fraction being associated to uncorrelated motions of the atoms. The present paper, however, justifies the basic interest for these oscillations in the theory of diffusion. In fact, they can be explained in the framework of a collective coordinate formulation, where the relevant Fourier components of the pair potential are only those corresponding to the wavevectors of the collective modes. Since the matrix elements for atomic scattering processes are proportional to the Fourier coefficients, it follows that, in this formulation, the only important processes are collisions where the wavevector change of an atom is a wavevector of the collective modes. A reduction in the number of these modes, as produced by a temperature rise, implies a reduction in the scattering processes and, subsequently, of the resistance presented by the liquid to the motion of a diffusing atom. This explains the strong rise with temperature of the self-diffusion coefficient, as recently observed in liquid lithium. Perturbation theory can be used to account for those Fourier components, which have been neglected in the above formulation. In this case, the results are fully consistent with the theory of diffusion developed earlier [M. Omini, Phil. Mag. 86 1643 (2006)]. 相似文献
20.
Yu. E. Lozovik O. L. Berman M. Willander 《Journal of Experimental and Theoretical Physics》1999,88(5):980-986
Instability in a system of interacting quasi-two-dimensional excitons in a type II superlattice of a finite thickness due
to attraction between oppositely-directed excitonic dipoles in neighboring layers has been discovered. A stable system is
that of indirect quasi-two-dimensional biexcitons formed by indirect excitons with dipole moments oriented in opposite directions.
The radius and binding energy of indirect biexcitons has been calculated. A collective spectrum of a system of such biexcitons
with a weak quadrupole interaction between them has been studied. Feasibility of Bose condensation, the density n
s(T) of the superfluid component, and a phase transition to the superfliud state in a low-density system of indirect biexcitons
have been analyzed.
Zh. éksp. Teor. Fiz. 115, 1786–1798 (May 1999) 相似文献