1. Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
2. University of Science and Technology of China, Hefei 230026, People's Republic of China
3. High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
4. School of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, People's Republic of China
5. Collaborative Innovation Centre of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China