1. Institute of Materials Science of Kaunas University of Technology, K. Baršausko St. 59, LT-51423 Kaunas, Lithuania
2. Department of Physics, Kaunas University of Technology, Studentu St. 50, LT-51368 Kaunas, Lithuania
3. Institut de Science des Matériaux de Mulhouse IS2M UMR 7361, 15 rue Jean Starcky, F 68100 Mulhouse, France