1. State University of Architecture and Building, Tomsk 634003, Russia
2. Institute of Solid State Physics, University of Latvia, Riga L V-1063, Latvia
3. Institute of Physics, University of Tartu, Tartu 50411, Estonia
4. L. N. Gumilyov Eurasian National University, Astana 010008, Kazakhstan
5. National Tomsk Polytechnic University, Tomsk 634050, Russia