1. Department of Condensed Matter Physics, University of P. J. Šafárik, Park Angelinum 9, 04001, Košice,
Slovakia
2. Department of Inorganic Chemistry, University of P.J. Šafárik, Moyzesova 11, 040 01, Košice,
Slovakia
3. Department of Condensed Matter Physics, ICMSE-CSIC, Sevilla University, P.O. Box 1065, 41080 Sevilla,
Spain