1. Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong S.A.R., P. R. China
2. Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong S.A.R., P. R. China
3. Far-Eastern Branch of Russian Academy of Sciences, Institute of Automation and Control Processes, Vladivostok 690041, Russia
4. Department of Physics and Center for Quantum Materials, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong S.A.R., P. R. China
5. TRACE EM Unit and Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong S.A.R., P. R. China
6. City University of Hong Kong Matter Science Research Institute (Futian, Shenzhen), Shenzhen 518048, P. R. China
7. Nanomanufacturing Laboratory (NML), City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, P. R. China