1. Center for Nanochemistry, Beijing Science and Engineering Centre for Nanocarbons, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
2. Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, P. R. China
3. State Key Laboratory of Silicon Materials and Center of Electron Microscopy, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China
4. International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
5. Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China