Energy spectrum for two-dimensional periodic potentials in a magnetic field.

The single-particle energy spectrum of two-dimensional electrons subject to a two-dimensional periodic potential and a perpendicular magnetic field is investigated. Effects of the potential shape as well as of Landau-level coupling are studied. In addition to the well-known recursive structure of the uncoupled Landau bands it is found that the steepness of the potential is decisive for the actual form of the spectra. The coupling between different Landau bands leads to an increased width of the magnetic subbands.