1. State Key Laboratory of Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China
2. Science, Mathematics and Technology, Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372, Singapore
3. School of Physics and Electronic Information Engineering, Engineering Research Center of Nanostructure and Functional Materials, Ningxia Normal University, Guyuan 756000, P. R. China
4. School of Physics and Telecommunication Engineering, Shaanxi Key Laboratory of Catalysis, Shaanxi University of Technology, Hanzhong 723001, People’s Republic of China
5. College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
6. Zhejiang University─University of Illinois at Urbana−Champaign Institute, Zhejiang University, Haining 310027, China
7. State Key Laboratory of Information Photonics and Optical Communications and School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, P. R. China
8. Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
9. Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing 100871, P. R. China
10. Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226000, P. R. China
11. Key Laboratory for the Physics and Chemistry of Nanodevices, Peking University, Beijing 100871, P. R. China