1. Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
2. Beijing National Laboratory
for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
3. Department of Physics
and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
4. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049, China
5. Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
6. Department of Physics, State Key Laboratory
of Surface Physics and Collaborative Innovation Center of Advanced
Microstructures, Fudan University, Shanghai 200433, China
7. International Center for Quantum Materials,
School of Physics, Peking University, Beijing 100871, China