1. A.M. Prokhorov General Physics Institute of RAS, 38, Vavilov str., Moscow 119991 Russia
2. Moscow Institute of Physics and Technology, 9, Institutskii per., Dolgoprudny, Moscow Region 141700, Russia
3. Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovak Republic
4. I. Frantsevich Institute for Problems of Materials Science, NAS, 3, Krzhyzhanovsky str., Kiev 03680, Ukraine
5. Moscow Engineering Physics Institute, 31, Kashirskoe Shosse, Moscow 115409, Russia