Wave vector dependent inter-Landau-level transitions in modulation-doped quantum wells

Inter-Landau-level transitions in two-dimensional electron gases under small magnetic field are observed by electronic Raman scattering due to finite wave-vector relaxation of the Deltan=0 selection rule. The spectrum of single-particle excitations becomes discretized as soon as the cyclotron energy overcomes the homogeneous broadening of the transitions. We have discovered that, at smaller fields, Landau quantization still strongly modifies the Raman response. Strong envelope oscillations are shown to result from overlap variations between Landau eigenfunctions at different wave vectors which persist at magnetic fields where the individual levels can no longer be energy resolved.