1. Department of Physics, Moscow State University, 119991 Moscow, Russia
2. Department of Applied Information Technology and Communication, Yuri Gagarin State Technical University of Saratov, Politechnicheskaya Street 77, Saratov 410054, Russia
3. Adámas Nanotechnologies, Inc., 8100 Brownleigh Dr, Suit 120, Raleigh, North Carolina 27617, United States