1. Department
of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
2. Institute
of Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznań, Poland
3. Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC), Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea
(EHU)-Materials Physics Center (MPC), Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain
4. Donostia International Physics Center (DIPC), Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain
5. Institute
of Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz
6, D-20146 Hamburg, Germany
6. Department
of Chemistry, Technical University Kaiserslautern, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany