1. Department of Physics and State Key Laboratory
of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
2. Collaborative Innovation Center
of Quantum Matter, Beijing 100084, China
3. College of Mechatronics
and Automation, National University of Defense Technology, Changsha 410073, China
4. College of Science, National University of Defense Technology, Changsha 410073, China
5. Beijing National Laboratory for Condensed
Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
6. State Key Laboratory of Surface Physics and Department
of Physics, Fudan University, Shanghai 200433, China
7. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800, China