1. I. Javakhishvili Tbilisi State University, E. Andronikashvili Institute of Physics, 6 Tamarashvili St., Tbilisi, 0177, Georgia
2. San Jose State University, One Washington Square, San Jose, CA 95192, USA
3. Institute of Materials Science, Physics-Sun Scientific Production Association, Uzbek Academy of Sciences, 2B G. Mavlyanova St., Tashkent, 700084, Uzbekistan