1. State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
2. Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
3. Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
4. Department of Physics, Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing 100872, China.
5. Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
6. RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.