1. Institute for Applied Physics and Center for Nonlinear Science University of Muenster Correnstrasse 2/4 Muenster 48149 Germany
2. Department of Physics Emory University N220 MSC, 400 Dowman dr. Atlanta GA 30322 USA
3. Institute of Metal Physics UB RAS 18 S. Kovalevslaya St Ekaterinburg 620108 Russia