Cyclotron resonance in GaAs/AlGaAs superlattices

Abstract

The cyclotron resonance of the GaAs/AlGaAs superlattice is studied by the generalized quantum Langevin equation approach to electronic transport. Divergences are eliminated from the conventional forms for the memory functions by inclusion of the effects of the fluctuation of the center of mass. In our theory there exists two resonance peaks in the CR absorption spectrum: the conventional magnetoplasmon absorption peak at the frequency ω ⩾ ω c, and another peak at ω ⩽ ω c due to the fluctuation effect. The positions, amplitudes, and the relative spacing of these two peaks depend mainly on the magnetic field, the electron density, the mobility of the sample and the temperature. Our results for the CR spectrum of a single layer GaAs/AlGaAs heterojunction are consistent with the experiments of Schlesinger et al. and of Muro et al. In calculating the CR spectrum of an infinite layer GaAs/AlGaAs superlattice, we find that the peak shift becomes larger and the peak width is almost unchanged when the superlattice periodicity is reduced.