[1] Harbin Inst Technol, Ctr Condensed Matter Sci & Technol, Harbin 150001, Peoples R China
[2] Dalian Univ Technol, Dept Phys, Dalian 116024, Peoples R China
[3] Jilin Univ, Dept Condensed Matter Phys, Changchun 130023, Peoples R China
[4] Acad Sinica, Int Ctr Mat Phys, Shenyang 110015, Peoples R China