D.A. Usanov - Dr. Sc. (Phys.-Math.), Professor, Head of Department of Solid State Physics, Saratov State University named after N.G. Chernyshevsky, Academic of RANS, Honored Scientist of RF. E-mail: UsanovDA@info.sgu.ru A.V. Skripal - Dr. Sc. (Phys.-Math.), Professor, Department of Solid State Physics, Saratov State University named after N.G. Chernyshevsky. E-mail: Skripala_v@info.sgu.ru D.V. Ponomarev - Ph. D. (Phys.-Math.), Associate Professor, Department of Solid State Physics, Saratov State University named after N.G. Chernyshevsky. E-mail: Ponomarev87@mail.ru E.V. Latysheva - Post-graduate Student, Department of Solid State Physics, Saratov State University named after N.G. Chernyshevsky. E-mail: Ekatushka@list.ru