1. Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
2. Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, Warsaw PL-02-668, Poland
3. Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
4. Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 761001, Israel