1. State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China
2. Department of Chemistry, The University of Hong Kong, Pokfulam 999077, P. R. China
3. Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
4. Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing 100871, P. R. China
5. Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226000, P. R. China
6. State Key Laboratory of Information Photonics and Optical Communications and School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, P. R. China
7. Key Laboratory for the Physics and Chemistry of Nanodevices, Peking University, Beijing 100871, P. R. China