A. M. Dyugaev

Rough model of a quantum liquid

As applied to condensed helium and hydrogen, a theory of quantum effects is suggested, one that is insensitive to the type of statistics of particles—the theory of quantum nondegenerate liquids. Evidently such a theory assumes that the mass of the atom and its polarization are small. For a zero-approximation, a system of hard spheres is chosen, and the attractive forces and the softness of the atom are considered to be small effects. The correlations between thermodynamic and kinetic characteristics of liquid He3 and He4 are obtained. On the basis of the experimental data for He4, and an isotropic law of the corresponding states for quantum systems with a large value of the de Boer parameter, all thermodynamic functions of liquid He3 are defined and tabulated in the regions of temperatures and molar volumes where they have not yet been measured. A rough model of a quantum liquid is suggested, based on the assumption of a dominating contribution by the diffusion excitations to the free energy of a dense condensed medium. The equation of state of the quantum liquid is derived. On the basis of the experimental data for He4, the equation of state of a quantum liquid consisting of hard spheres is compared with the similar equations obtained by a numeric computer simulation. The energy of the ground state of spin-oriented condensed hydrogen isotopes is defined.

Negative Ca− and Ba− ions of large radius on the surface and in the volume of liquid helium

Negative Ca− and Ba− ions of large radii on the surface of and in bulk liquid helium have been studied. Our results indicate that these ions are adsorbed on the helium surface. Ions on free liquid helium surfaces have not been studied previously because it was thought impossible to confine them on the surface. Ca− and Ba− ions have very low binding energies, therefore, like electrons, they form a bubble of large radius in bulk helium, whose energy is higher than on the surface. The behavior of ions on the surface exhibits a number of previously unknown features owing to their large masses and strong localization in the horizontal plane. Even in the absence of confining electric field, a hole is formed under an ion due to the polarization attraction between the liquid helium and the charged ion. This hole formation reduces the ion mobility by several orders of magnitude and increases its effective mass severalfold. The critical density of electrons and ions is approximately the same on the surfaces of thin and thick helium films.

Lift of degeneracy of Landau levels of 2D electron gas by point-like impurities

We study the density of states of two-dimensional electron gas in magnetic field with scattering on point-like impurities that are uniformly distributed along the sample. We show that the electron-impurity interaction completely lifts the degeneracy of the Landau levels even at low impurity concentration. This statement is in contradiction with the previous results obtained in the unphysical approximation of two-dimensional impurities. There is a large region of the electron energy

Properties of a magnetic impurity in a metal

\omega

Point impurities remove degeneracy of the Landau levels in a two-dimensional electron gas

, counted from the Landau level, where the density of states

Surface tension of pure liquid helium isotopes

\rho (\omega)

Theory of the resonant properties of electrons localized on the surface of liquid helium

is inversely proportional to

Aharonov-Bohm effect for electrons on a liquid-helium surface

|\omega|

Charged macroparticles over liquid helium

and proportional to the impurity concentration. Our results are applicable to different 2D electron systems as heterostructures, inversion layers and interfaces.We show that a magnetic field can influence the proximity effect in NS junctions via diamagnetic screening current flowing in the superconductor. Using ballistic quasi-one-dimensional (Q1D) electron channels as an example, we show that the supercurrent flow shifts the proximity-induced minigap in the excitation spectrum of a Q1D system from the Fermi level to higher quasiparticle energies. Thermal conductance of a Q1D channel (normalized by that of a normal Q1D ballistic system) is predicted to manifest such a spectral feature as a nonmonotonic behavior at temperatures corresponding to the energy of excitation into the gapful part of the spectrum.

Diffusion transport of negative ions through the interface between cryogenic liquids

The effect of a polarized conduction-electron cloud back on a magnetic impurity dissolved in a metal is studied. It is shown that at a temperature Tc much higher than the Kondo temperature the system becomes unstable against symmetry breaking and that a state with 〈Sz〉 ≠ 0 is established. The behavior of 〈 Sz〉 is derived for all temperatures and magnetic fields except for a very narrow region around Tc and for very low temperatures. The minute role of Kondo-type processes in establishing the symmetry-broken state is pointed out.