ISSN:1063-777X    

DOI:10.1063/1.593414

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The results of experimental investigations of diffusion processes in solid helium are reviewed. It is shown that3Heimpurities in hcp4Heare narrow-band quasiparticles whose motion can be adequately described in the existing theory of quantum diffusion. The observed peculiarities of3Hediffusion in the bcc phase of concentrated3He–4Hesolutions, i.e., a noticeable diffusive transport at concentrations higher than critical, the independence of the diffusion coefficientDon the concentration forx<20&percent;3He,an abrupt increase inDforx≃20&percent;,and a dependence ofDon the diffusion length in the latter case, have not received a quantitative interpretation. The relation between diffusion phenomena in concentrated solutions and the percolation problem is emphasized. The results of experiments on vacancy diffusion are analyzed, and it is proved that vacancies in3He–4Heare wide-band quasiparticles. ©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593334

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

This paper presents a brief review of the electron properties in two-dimensional systems which contain zero-range scatterers which are subjected to a magnetic field. The electron spectrum is described for a periodic arrangement of point scatterers and rational magnetic flux per unit cell. Delocalized states on the Landau levels are constructed for the case of positional disorder. The electron localization in a one-dimensional disordered set of scatterers is studied. Application to the study of electron transmission through quantum dots and ballistic channels is reviewed. ©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593330

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

An algorithm for calculating the surface impedance of a normal isotropic metal is constructed by taking into account the arriving term in the collision integral (in the case of specular reflection). Analytic expressions are obtained for scattering probability describing thes-,p-, andd-scattering. ©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593331

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The dependence of the resistance of a layered conductor with an arbitrary quasi-two-dimensional electron energy spectrum on the magnitude and orientation of a magnetic field relative to the layers is analyzed. It is shown that, when the current flows along the normal to the layers, the resistance of the sample depends significantly on the angle&thgr;between the normal and the strong magnetic field vector; for&thgr;=&pgr;/2,the resistance increases linearly with the magnetic field in a wide range of magnetic fields.©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593332

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The surface magnetization of metals associated with electrons whose orbits are tangential to the metal boundary is investigated, taking into account anisotropy in the energy spectrum of conduction electrons. It is shown that the angular dependence of magnetization has peculiarities determined by the curvature of the Fermi surface at the reference points. Explicit expressions have been obtained for the surface magnetic susceptibility of electrons in bismuth, and appropriate numerical estimates of its value have been made. ©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593333

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A mathematical method based on a reduced representation of the electron–electron collision operator acting in the space of quasi-equilibrium functions is constructed. A number of kinetic phenomena such as the evolution of highly anisotropic and high-energy electron distributions, the quasi-hydrodynamic effect in electrical conduction, and a new nonlinear transport mode are described from a unified point of view. Kinetic effects which can be observed in experiments on electron beam propagation and electrical conduction of (GaAs)Al wires with a high mobility of charge carriers are predicted. ©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593335

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The Lifshits method of local perturbations is used for studying the properties of a two-dimensional electron-impurity system in a quantizing magnetic field perpendicular to the plane of electron motion. The high-frequency conductivity tensor of the system is calculated in the model of independent point impurity atoms, taking into account the impurity states of electrons and spatial dispersion. The dissipative component of the conductivity has narrow resonant peaks at frequencies of electron transitions between the Landau levels and local levels, which are induced by the magnetic field. In zero magnetic field, these peaks merge into one broad peak lying above the threshold frequency for electron transitions from a local level to the energy band. Numerical values of the peak heights are obtained for semiconducting structures with a two-dimensional electron gas. ©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593336

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The theory of finite-dimensional perturbations of self-adjoint operators, which is aimed at the solution of physical problems, is reviewed. Special attention is paid to the special kind of operators, which permits efficient application of theJ-matrix technique. The spectral density of a periodicJ-matrix is calculated. ©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593337

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The waves localized near the free surface (001) of a fcc crystal and propagating along the [110] direction are analyzed in the model of central interaction of nearest neighbors. The frequencies of these waves fall in the gaps of the frequency spectrum of bulk harmonic vibrations for a fixed value of the wave vectorkalong the surface. The long-wave limit and the case of wave vectors close to the Brillouin zone boundary are studied analytically. These limiting dependences are in accord with the results obtained earlier by other authors by numerical methods. The analytical calculations in the limiting intervals of vectorkare supplemented with numerical calculations for arbitrary values of wave vectors. It is significant that the waves under investigation have a displacement component perpendicular to the crystal surface and hence can be studied by standard methods of inelastic scattering of helium atoms. ©1997 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593338

出版商:AIP    

年代:1997

数据来源: AIP