1. Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
2. Max Planck Institute of Microstructure Physics, Halle 06120, Germany
3. Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
4. Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
5. International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
6. Institut für Theoretische Physik und Astrophysik Universität Würzburg, 97074 Würzburg, Germany