1. Department of Experimental Physics, Faculty of Fundamental Problems of Technology, University of Science and Technology, St. Wyspiańskiego 27, 50-370 Wrocław, Poland
2. Technische Physik, University of Würzburg and Wilhelm-Conrad-Röntgen-Research Center for Complex Material Systems, Am Hubland, D 97074 Würzburg, Germany
3. SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, KY16 9SS St. Andrews, United Kingdom
4. Institute of Nanostructure Technologies and Analytics, Technische Physik, Universitaet Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany