1. Andrew and Erna Viterbi Department of Electrical Engineering and Russell Berrie Nanotechnology Institute, Technion, Haifa 32000, Israel
2. Institute of Nanostructure Technologies and Analytics, Technische Physik, CINSaT, University of Kassel, Kassel 34132, Germany
3. Department of Applied Physics, Hebrew University, Jerusalem 91904, Israel
4. E. L. Ginzton Laboratory, Applied Physics Department, Stanford University, Stanford, California 94305, USA
5. Department of Physics, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India