1. National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
2. Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng 224051, People's Republic of China
3. School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, People's Republic of China
4. Computational Condensed Matter Physics Laboratory, Riken, Wako, Saitama 351-0198, Japan