1. B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences ofUkraine, 47 Nauky Ave., Kharkiv 61103, Ukraine
2. National Technical University “Kharkiv Polytechnical Institute”, 2 Kyrpychova Str., Kharkiv 61002, Ukraine
3. Universite Aix-Marseille, CNRS, MADIREL, Marseille 13396, France
4. Department of Physics and Astronomy, University of Missouri, Columbia MO, USA