1. O.O. Galkin Donetsk Institute for Physics and Engineering, National Academy of Sciences of Ukraine, 46 Nauki Ave., Kyiv 03028, Ukraine
2. Vasyl’ Stus Donetsk National University, 600-richya Str. 21, Vinnytsia 21021, Ukraine
3. G.V. Kurdyumov Institute for Metal Physics, National Academy of Sciences of Ukraine, 36 Academician Vernadsky Blvd., Kyiv 03142, Ukraine
4. Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, 5 Helmholtzweg, Jena 07743, Germany