HALL CONDUCTIVITY AND OPTICS OF A TWO-DIMENSIONAL ELECTRON GAS AT THE LACK OF INVERSION SYMMETRY

Abstract

Quantum states of 2D electrons are studied in a periodic potential without the inversion center in the presence of a magnetic field. It is shown that the energy spectrum in magnetic subbands is not symmetric with respect to the center of magnetic Brillouin zone: E(k)≠E(-k). Singularities (phase branching points) of the electron wave function, which determine the quantization law of Hall conductivity σxy, are studied in the k space. It is found that the number of singular points and the correspondent topological invariants which determine Hall conductivity of occupied subbands change drastically with respect to variation of periodic potential parameters. It is predicted that in such system the photogalvanic effect can be observed under the action of external electromagnetic field.