1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
4. South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China