1. Advanced Research Center for Nanolithography (ARCNL) 1 , Science Park 106, 1098XG Amsterdam, The Netherlands
2. Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam 2 , Science Park 904, 1098 XH Amsterdam, The Netherlands
3. Department of Materials Science and Engineering, The University of Sheffield 3 , Sheffield S1 3JD, United Kingdom