1. NANOTECH Centre, Ural Federal University, 620002 Ekaterinburg, Russia
2. Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
3. Physics Department, Tanta University, 31527 Tanta, Egypt
4. Institute of Metallurgy, Ural Branch of Russian Academy of Sciences, 620016 Ekaterinburg, Russia