1 Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany.
2 Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100, Torun, Poland.
3 Institute of Physical Chemistry, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany.
4 Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany.
5 Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100, Torun, Poland. karolina@fizyka.umk.pl.