1. School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, People’s Republic of China
2. Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, People’s Republic of China
3. School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
4. State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China