1. International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
2. Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
3. Beijing National Laboratory for Condensed Matter Physics and the Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
4. Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA.