1. Institute of Physics, NAS of Ukraine 1 , 46 Nauky Ave., Kyiv 03028, Ukraine
2. Institute of Magnetism, NAS of Ukraine and MES of Ukraine 2 , 36-b Vernadskogo Blvd., Kyiv 03142, Ukraine
3. National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute,” 3 37 Beresteiskyi Ave., Kyiv 03056, Ukraine