1. National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, People’s Republic of China
2. College of Physics Science, Henan University of Science and Technology, Luoyang 471023, People’s Republic of China
3. Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People’s Republic of China