1. The State Key Lab of Mechanical Transmissions, Chongqing University, Chongqing 400044, People's Republic of China
2. Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong
3. College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158, People's Republic of China
4. School of Materials Science and Engineering, Nanchang University, Nanchang 330031, People's Republic of China