Magnetophonon resonance in high density, high mobility quantum well systems

We have investigated the magnetophonon resonance (MPR) effect in a series of single GaAs quantum well samples which are symmetrically modulation doped in the adjacent short period AlAs/GaAs superlattices. Two distinct MPRseries are observed originating from the Γ and X electrons interacting with the GaAs and AlAs longitudinal optic (LO) phonons respectively. This confirms unequivocally the presence of X electrons in the AlAs quantum well of the superlattice previously invoked to explain the high electron mobility in these structures [Friedland et al., Phys. Rev. Lett 77, 4616 (1996)].