1. Key Laboratory of Materials Physics
2. Institute of Solid State Physics
3. Chinese Academy of Sciences
4. Hefei 230031
5. P. R. China
6. Faculty of Materials Science and Engineering
7. Kunming University of Science and Technology
8. Kunming
9. China
10. College of Microtechnology & Nanotechnology
11. Qingdao University
12. Qingdao