1. Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava 1 , Mlynská Dolina F2, Bratislava 842 48, Slovakia
2. Thin Film Physics Division, Department of Physics (IFM), Linköping University 2 , Linköping SE-581 83, Sweden
3. Faculty of Materials Science and Engineering, Warsaw University of Technology 3 , 141 Woloska St., 02-507 Warsaw, Poland
4. Institute of Materials and Machine Mechanics, Slovak Academy of Sciences 4 , Dúbravská cesta 9, Bratislava 845 11, Slovakia