1. Institut de Physique de Rennes,
CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
2. Centre de Recherche Paul-Pascal,
CNRS UPR 8641, Université de Bordeaux 1, 33600 Pessac, France
3. Experimental Physics, Saarland University, 66041 Saarbrücken, Germany
4. Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany
5. Faculty of Electrical Engineering, Czestochowa University of Technology, 42-200 Czestochowa,
Poland
6. Laboratoire Léon Brillouin (CEA-CNRS), CEA Saclay, 91191 Gif sur Yvette,
France
7. BAM Bundesanstalt für Materialforschung und −prüfung, 12205 Berlin, Germany