Magnetoplasmon-phonon coupling in semiconductor quantum wells

The collective excitations of a double heterostructure in the presence of a magnetic field are examined in detail. The polarization function of the quasi-two-dimensional electron gas in the presence of a perpendicular quantizing magnetic field is calculated within various long-wave approximations and in the random-phase approximation. Using these polarization functions the dispersion curves of the coupled intra- and inter-subband magnetoplasmon-phonons are calculated and plotted in graphical form. The calculation of the dispersion relation is done for GaAs-Ga 1-x Al x As double heterostructures and include both quantum size effects and the correct spectrum of the long-wave optical phonons. In this paper the higher resonances of the quasi-two-dimensional magnetoplasma, the Bernstein modes, are also investigated. It is shown that the intra- and inter-subband magnetoplasmon-phonons are free of Landau damping for finite perpendicular quantizing magnetic fields.