Evolution of energy levels of a GaAs/AlGaAs superlattice under the influence of a strong magnetic field

We present photocurrent spectra of the Wannier-Stark ladder of a GaAs/AlGaAs superlattice in a magnetic field up to 9 T and oriented along the growth direction of the superlattice. The Landau and Wannier-Stark quantization directions are perpendicular to each other. The salient observation is the evolution of Landau fans for the different Wannier-Stark transitions with the Landau fan assigned to the spatially direct Wannier-Stark-ladder transitions being very pronounced quite in contrast to the Landau fans for the spatially indirect Wannier-Stark transitions which are weak