1. Center for Physical Sciences and Technology,Vilnius,Lithuania,LT-10257
2. Institute of Physics, PAS, Al. Lotnikóv 32/46,International Research Centre MagTop,Warsaw,Poland,02-668
3. Fraunhofeer-Institut für Angewandte Festkörperphysik, Tullastrasse 72,Freiburg,Germany,D-79108