1. State Key Laboratory of Material Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan Hubei 430074 China
2. Center for Functional Nanomaterials Brookhaven National Laboratory Upton NY 11973 USA
3. Frontier Institute of Chemistry Frontier Institute of Science and Technology jointly with College of Science Xi'an Jiaotong University Xi'an Shanxi 710054 China
4. Department of Physics and Astronomy California State University Northridge CA 91330 USA
5. Current address: School of Physical Science and Technology Inner Mongolia University Hohhot Inner Mongolia 010021 China
6. Faculty of Materials Science and Chemistry China University of Geosciences Wuhan Hubei 430074 China
7. College of Materials Science and Engineering Changsha University of Science and Technology Changsha 410114 China
8. School of Materials Science and Engineering & National Institute for Advanced Materials Nankai University Tianjin 300350 China
9. Current address: Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China