Moskalenko E.S.1,2, Karlsson K.F.1, Donchev V.3, Holtz P.O.1, Schoenfeld W.V.4, Petroff P.M.4
1Department of Physics and Measurement Technology, Linkoping University, Linkoping, Sweden
2A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia
3Faculty of Physics, Sofia University, Sofia, Bulgaria
4Materials Department, University of California, Santa Barbara, California, USA