1. Laboratory of Condensed Matter Physics, University of Picardie, 33 rue St. Leu, Amiens 80039, France
2. Life Chemicals Inc., Murmanska st. 5, Kyiv 02660, Ukraine
3. Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588-0299, USA
4. Faculty of Physics, Southern Federal University, 5 Zorge Str., 344090 Rostov-on-Don, Russia