1. Prokhorov General Physics Institute, RAS, 119991, Vavilov Str. 38, Moscow, Russia
2. Moscow Institute of Physics and Technology, 141700, Institutsky lane 9, Dolgoprudniy, Russia
3. Frantsevich Institute for Problems of Materials Science of NASU, Krzhyzhanovskii Str. 3, 03680 Kiev, Ukraine
4. Institute of Experimental Physics, SAS, Watsonova Str. 47, SK-04001 Košice, Slovak Republic