1. Faculty of Materials, Metallurgy and Recycling, Technical University of Kosice, Letna 9, 040 01 Kosice, Slovakia
2. Centre for Progressive Materials, Technology, and Innovation Park, Pavol Jozef Safarik University in Kosice, Tr. SNP 1, 040 11 Kosice, Slovakia
3. FZU—Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 00 Prague, Czech Republic
4. Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice, Slovakia