1. Beijing National
Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
2. School of Physics, University of Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
3. Laboratory
for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan
4. Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer
Straße 40, 01187 Dresden, Germany
5. National Synchrotron Radiation Research Center, 101
Hsin-Ann Road, Hsinchu 30077, Taiwan
6. Department of Physics, National Tsing Hua University, 101 Section 2 Kuang-Fu Road, Hsinchu 30013, Taiwan
7. Collaborative Innovation Center of Quantum Matter, Beijing 100190, People’s Republic of China