1. G.V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Blvd., UA-03680 Kyiv-142, Ukraine
2. A.V. Shubnikov Institute of Crystallography of RAS, 59 Leninskiy Ave., 119333 Moscow, Russia
3. National Research Centre ‘Kurchatov Institute’, 1 Kurchatov Sq., 123182 Moscow, Russia
4. V.E. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41 Nauky Ave., 03028 Kyiv, Ukraine