Stress and the van hove singularities of hole magnetoplasmons

The hole magnetoplasmon dispersion of GaAs/AlGaAs heterostructures is calculated in the presence of uniaxial stress using a time-dependent Hartree-Fock approximation which becomes exact in the limit of large Landau level separations. We find that the stress affects both the magnitude of cyclotron resonance positions shifted by hole-hole interactions and the sharpness of the Van Hove singularities present in the density of states of hole magnetoplasmons. Both results are consequences of strong heavy and light hole mixing, and differ from the case of an electron gas, where cyclotron resonance position shifts are forbidden by Kohn's theorem. The dependence of the singularities on the applied uniaxial stress should provide a test of our theory.