1. Department of Physics, City University of Hong Kong, Kowloon 999077, Hong Kong, China
2. Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay 999077, Hong Kong, China
3. Shenyang National Laboratory (SYNL) for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
4. School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China