Collective elementary excitations of two–dimensional magnetoexcitons interacting with plasmons under the influence of excited Landau levels

Abstract

The energy spectrum of the collective elementary excitations consists of two exciton-type branches (energy and quasienergy branches), each of them with an energy gap and a roton-type region, from the gapless optical plasmon branch and from the acoustical plasmon branch, which reveals an absolute instability in the range of small and intermediary wave vectors.