1. School of Materials Science and Engineering
2. Central South University
3. Changsha 410083
4. China
5. Beijing National Laboratory for Condensed Matter Physics
6. Institute of Physics
7. Chinese Academy of Sciences
8. Beijing 100190
9. P. R. China
10. Key Laboratory of Green-Chemistry Materials in University of Yunnan Province
11. School of Chemistry & Environment
12. Yunnan Minzu University
13. Kunming 650500
14. P.R. China
15. Department of Physics
16. Georgia Southern University
17. Statesboro
18. USA