1. Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
2. Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia.
3. Laboratory of Theoretical Physics and Statistical Models (LPTMS)–CNRS, UMR 8626, Université Paris-Sud, F-91405 Orsay, France.
4. Center of Excellence in Nanoscience and Nanotechnology (CENN) Nanocenter, Jamova 39, SI-1000 Ljubljana, Slovenia.
5. Faculty of Electrical Engineering, University of Ljubljana, Tržaška 21, SI-1000 Ljubljana, Slovenia.
6. Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia.