1. School of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
2. Physics Department, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 91058, Germany
3. Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52428, Germany
4. RWTH Aachen University, Aachen 52062, Germany