1. College of Applied Sciences
2. Beijing University of Technology
3. Beijing 100124
4. P. R. China
5. State Key Laboratory of New Ceramics and Fine Processing
6. School of Materials Science and Engineering
7. Tsinghua University
8. Beijing 100084
9. State Key Laboratory of Low-Dimensional Quantum Physics
10. Tsinghua-Foxconn Nanotechnology Research Center
11. Department of Physics
12. Collaborative Innovation Center of Quantum Matter
13. Fudan University
14. Shanghai 200433
15. School of Physics and Optoelectronic Technology
16. Dalian University of Technology
17. Dalian 116024