1. Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine 1 , Svientsitskii Street 1, 79011 L’viv, Ukraine
2. Departamento de Fisica, Universidade Federal de Lavras 2 , CP 3037, 37200-000 Lavras-MG, Brazil
3. Department of Metal Physics, Ivan Franko National University of L’viv 3 , Kyrylo and Mephodiy Street 8, 79005 L’viv, Ukraine