1. Osnabrück University, Department of Physics, 49076 Osnabrück, Germany
2. M.N. Miheev Institute of Metal Physics, 620137 Yekaterinburg, Russia
3. Ural Federal University, 620137 Yekaterinburg, Russia
4. Ural State Mining University, 620137 Yekaterinburg, Russia
5. II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
6. University of Silesia, Department of Physics, 40-007 Katowice, Poland