1. Third Institute of Physics, University of Stuttgart, Allmandring 13, 70569 Stuttgart, Germany
2. Materials Research and Technology (MRT) Department, Luxembourg Institute of Science and Technology (LIST), 4422 Belvaux, Luxembourg
3. Department of Physics and Materials Science, University of Luxembourg, 4422 Belvaux, Luxembourg
4. Universität des Saarlandes, Fachrichtung Physik, Campus E2.6, 66123 Saarbrücken, Germany
5. fourth Physics Institute and Reseach Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70569, Stuttgart, Germany
6. Department of Physics, Chemistry and Biology, Linköping University, 581 83 Linköping, Sweden
7. Leibniz-Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany
8. Max Planck Institute for Solid State Research, Heisenbersgtraße 1, 70569 Stuttgart, Germany