1. Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N-Orsay, 91405 Orsay cedex, France
2. Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan
3. Singulus Technology AG, Hanauer Landstrasse 103, 63796 Kahl am Main, Germany