1. RVmagnetics a.s., Hodkovce 21, 04421 Košice, Slovakia
2. Institute of Physics, Faculty of Sciences, P.J. Safarik University, Park Angelinum 9, 041
54 Košice, Slovakia
3. Department of Physics, FEEI, TUKE, Park Komenského 2, 042 00 Košice, Slovakia
4. Institute of Material Science of Madrid, CSIC, 28049 Madrid, Spain