1. Institute of Theoretical Physics, Shanxi University, Taiyuan, Shanxi 030006, China
2. Department of Physics, College of Science, Shenzhen University, Shenzhen 518060, China
3. Key Laboratory of Materials Science, Institute of Solid State Physics, Chinese Academy of Science, Hefei 230031, China
4. Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China