1. State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing 100084 China
2. State Key Lab of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China
3. Department of Physics Durham University Durham DH1 3LE UK
4. Department of Materials Science and Engineering National Chiao Tung University Hsinchu 30010 Taiwan
5. Department of Physics National Cheng Kung University Tainan 70101 Taiwan
6. Department of Materials Science and Engineering Pennsylvania State University University Park PA 16802 USA
7. Collaborative Innovation Center of Quantum Matter Beijing 100084 China
8. RIKEN Center for Emergent Matter Science Wako 351‐198 Japan