Theoretical study of materials (semiconductors and superconductors) of micrometer and nanometer size. The electrical, magnetic and optical properties of such nanostructures are studied using theoretical modelling and computer simulations. This is the so-called area of mesoscopic physics and nanophysics. New hybrid systems consisting of combinations of semiconductors and ferromagnets or superconductors are investigated. The goal is the increase of the functionality of semiconductor structures. An important aspect of the research is the interaction with experiment. An active collaboration exists with several experimental and theoretical groups over the world.