1. Galatea Lab, STI/IMT, École Polytechnique Fédérale de Lausanne (EPFL), Rue de La Maladière 71b, CH-2002 Neuchâtel, Switzerland
2. Aix-Marseille University, CNRS, LP3 UMR 7341, 13288 Marseille, France
3. Electron Spectroscopy and Microscopy Laboratory, SB/IPHYS, École Polytechnique Fédérale de Lausanne (EPFL), Section 3, CH-1015 Lausanne, Switzerland
4. Shanghai Institute of Optics and Fine Mechanics, 899 Huiwang E Rd., Jiading Qu, Shanghai Shi 201800, China