Institution: | 1. Institut für Physik, Universität Oldenburg, Postfach 2503 D-26111 Oldenburg, Germany;2. Institute for Basic Research, Eurasian National University, Astana 010008, Kazakhstan;3. Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek 720071, Kyrgyzstan;4. Department of General and Theoretical Physics, Eurasian National University, Astana 010008, Kazakhstan |