1. nanotech@surfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology Überlandstrasse 129, 8600 Dübendorf, Switzerland
2. Laboratory for Magnetic and Functional Thin Films, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
3. Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
4. Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland