1. Belarus State University of Informatics and Radioelectronics, P. Browka 6, 220013 Minsk, Belarus
2. CNR/INFM Laboratorio Regionale SuperMat and Dipartimento di Fisica “E.R. Caianiello” Università degli Studi di Salerno, Baronissi (Sa), I84081, Italy
3. Kamerling Onnes Laboratory, Leiden University, P.O.Box 9504, 2300 RA Leiden, The Netherlands