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