1. Institute
of Micro- and Nanotechnologies MacroNano, Technische Universität Ilmenau, Gustav-Kirchhoff- Str.7, D-98693 Ilmenau, Germany
2. Leibniz
Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstraße
20, 01069 Dresden, Germany
3. Institute
of Physics, Kazan Federal University, Kremlyovskaya Str. 18, Kazan, Russia