1. Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Forschungszentrum Jülich, Fürther Straße 248, 90429 Nürnberg, Germany
2. Institute for Theoretical Physics, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany
3. Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands
4. Department of Physics, Bar-Ilan University, 52900 Ramat Gan, Israel
5. Université de Liège, GRASP Lab, CESAM Research Unit, Allée du 6 Août 19, Liège 4000, Belgium