1. Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainer Strasse 70, 09107 Chemnitz, Germany
2. Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany
3. Institute for Solid State Research, Leibniz IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany
4. Institute of Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
5. Physics Department, V. Karazin National University, Svobody Sq. 4, Kharkiv 61077, Ukraine