Observation of coupled quasi-two-dimensional electronic excitations in tilted magnetic fields

Abstract

We report on a magneto-Raman scattering investigation of free and donor-bound electrons in GaAs/AlxGa1-xAs quantum wells. For fields perpendicular to the layers, the spectra show intersubband transitions of photoexcited electrons and ls-->ls' donor excitations. Tilted fields lead to subband-Landau level and ls'-2p+ coupling. Experimental results for the latter case agree very well with variational calculations. Data on combined intersubband-cyclotron resonances at arbitrary tilt angles are accurately described by expressions valid for parabolic wells. The parabolic approach is shown to provide a good approximation in situations where coupling to higher subbands can be neglected.