1. Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Forschungszentrum Jülich, Erlangen, Germany
2. Department of Physics and Astronomy, University of Padova, Padova, Italy
3. INFN, Sezione di Padova, Padova, Italy
4. Dep. Est. de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Madrid, Spain
5. GISC – Grupo Interdisciplinar de Sistemas Complejos, Madrid, Spain