1. Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02-668 Warszawa, Poland
2. Physikalisches Institut, Experimentelle Physik III, Universität Würzburg, D-97074 Würzburg, Germany
3. International Research Center MagTop, Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02-668 Warszawa, Poland