O. G. Balev

Electron correlation effects in a wide channel from the ν = 1 quantum Hall edge states

The spatial behavior of Landau levels (LLs) for the

Two-subband electron transport in nonideal quantum wells

nu=1

Effect of a periodic modulation on edge magnetoplasmons in the quantum Hall regime

quantum Hall regime at the edge of a wide channel is studied in a self-consistent way by using a generalized local density approximation proposed here. Both exchange interaction and strong electron correlations, due to edge states, are taken into account. They essentially modify the spatial behavior of the occupied lowest spin-up LL in comparison with that of the lowest spin-down LL, which is totally empty. The contrast in the spatial behavior can be attributed to a different effective one-electron lateral confining potentials for the spin-split LLs. Many-body effects on the spatially inhomogeneous spin-splitting are calculated within the screened Hartree-Fock approximation. It is shown that, far from the edges, the maximum activation energy is dominated by the gap between the Fermi level and the bottom of the spin-down LL, because the gap between the Fermi level and the spin-up LL is much larger. In other words, the maximum activation energy in the bulk of the channel corresponds to a highly asymmetric position of the Fermi level within the gap between spin-down and spin-up LLs in the bulk. We have also studied the renormalization of the edge-state group velocity due to electron correlations. The results of the present theory are in line with those suggested and reported by experiments on high quality samples.

EDGE MAGNETOPLASMONS FOR VERY LOW TEMPERATURES AND SHARP DENSITY PROFILES

Electron transport in nonideal quantum wells (QWs) with large-scale variations of energy levels is studied when two subbands are occupied. Although the mean variations of these two levels are screened by the in-plane redistribution of electrons, the energies of both levels remain nonuniform over the plane. The effect of random inhomogeneities on the classical transport is studied within the framework of a local response approach for weak disorder. Both short-range and small-angle scattering mechanisms are considered. Magnetotransport characteristics and the modulation of the effective conductivity by transverse voltage are evaluated for different kinds of confinement potentials (hard-wall QW, parabolic QW, and stepped QW).

Magnetoplasmons in nondegenerate quantum wires on suspended helium films

Abstract A random-phase approximation treatment of edge magnetoplasmons (EMPs) in the quantum Hall regime is presented when a weak periodic potential is imposed along the Hall bar length. We show for filling factor ν =1(2) that the unidirectional periodic potential reshapes essentially the spatial structure of the fundamental EMP, normal and parallel to the edge, and leads to the appearance of a novel fundamental EMP. We find a strong renormalization of the usual fundamental EMP, which depends on the modulation parameters. The novel mode has an acoustical dispersion relation with phase velocity almost equal to the group velocity of the edge states.