1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
2. Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
3. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100190, China
4. Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China