1. School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
2. State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 10084, China
3. ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
4. Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, China