1. CAS Key Laboratory of Design and Assembly of Functional NanostructuresFujian Institute of Research on the Structure of MatterChinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
2. Laboratory of Advanced Functional MaterialsXiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of Sciences Xiamen 361021 P. R. China
3. Institute of Electrical EngineeringChinese Academy of Sciences Beijing 100190 P. R. China
4. University of Chinese Academy of Sciences Beijing 100049 P. R. China