1. Physikalisches Institut III, Universität Erlangen-Nürnberg, Erwin-Rommel-Strasse 1, 91058 Erlangen, Paul Verlaine University - LPMD/IPC, 1 Bd. Arago, F-57078 Metz, France, and Institute of Metal Physics, S. Kowalewskoi 18, 620219 Yekaterinburg, Russia, School of Engineering and Science, International University Bremen, P.O. Box 750 561, 28725 Bremen, Germany