1. Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering and College of Engineering, and BIC-ESAT, Peking University, Beijing 100871, P. R. China
2. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
3. School of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
4. Department of Physics and Center for Quantum Materials, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR 999077, P. R. China
5. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, P. R. China
6. Center for Integrarive Materials Discovery, Department of Chemistry and Chemical and Biomedical Engineering, University of New Haven, West Haven, Connecticut 06516, United States