1. Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, Jána Bottu 8857/25, Trnava 917 24, Slovakia
2. Centre of New Technologies, University of Warsaw, Banacha 2c, 02097 Warsaw, Poland
3. Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava, Slovakia