1. Institute of Advanced Magnetic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310012, China
2. Department of Applied Physics, Hong Kong Polytechnic University, Hong Kong, China
3. Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China
4. Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maxilimians-Universität München, 80539 München, Germany
5. School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
6. Istituto di Fotonica e Nanotecnologie - CNR, 00156 Roma, Italy
7. Vacuum Interconnected Nanotech Workstation (NANO-X), Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
8. The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom