1. National Technical University “Kharkov Polytechnic Institute”, 21 Frunze Str., Kharkov, 61002, Ukraine
2. B. Verkin Institute for Low Temperature Physics and Engineering, 47 Lenin Ave., Kharkov, 61103, Ukraine
3. Institut des Matériaux Jean Rouxel, University of Nantes, CNRS, UMR 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex
3, France