1. Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
2. Slovak University of Technology, Centre for Nanodiagnostics, Vazovova 5, 812 43 Bratislava, Slovakia
3. Department of Lithospheric Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
4. Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Prague 6, Czech Republic
5. Faculty of Electrical Engineering, Czech Technical University, Technická 2, Prague 6, Czech Republic