1. School of Physics
2. University of Electronic Science and Technology of China
3. Chengdu 610054
4. China
5. School of Materials
6. Department of Physics and Astronomy
7. University of Missouri
8. Columbia
9. USA
10. College of Chemistry and Chemical Engineering
11. Xiamen University
12. Xiamen 361005
13. P. R. China
14. Department of Materials Science and Engineering
15. Department of Physics
16. Lanzhou City University
17. Lanzhou 730070
18. University of New South Wales
19. Sydney
20. Australia