1. State Key Laboratory for Artificial Microstructure and Mesoscopic Physics and School of PhysicsPeking University Beijing 100871 China
2. State Key Laboratory of Superlattices and MicrostructuresInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
3. Electron Microscopy LaboratorySchool of PhysicsPeking University Beijing 100871 China
4. National Center for Materials Service SafetyUniversity of Science and Technology Beijing Beijing 100083 China
5. Collaborative Innovation Center of Quantum Matter Beijing 100871 China
6. International Center for Quantum MaterialsSchool of PhysicsPeking University Beijing 100871 China
7. National Institute for Materials Science 1‐1 Namiki Tsukuba 305‐0044 Japan