1. School of Physics and Materials Science, Nanchang University, Nanchang 330031, China
2. Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, China
3. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
4. Hubei Key Laboratory of Micro- & Nano electronic Materials and Devices, School of Microelectronics, Hubei University, Wuhan 430062, China
5. Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China