[1] SHANGHAI JIAO TONG UNIV,DEPT PHYS,SHANGHAI 200030,PEOPLES R CHINA
[2] SHANGHAI JIAO TONG UNIV,DEPT APPL PHYS,SHANGHAI 200030,PEOPLES R CHINA
[3] CHINA CTR ADV SCI & TECHNOL,WORLD LAB,CTR THEORET PHYS,BEIJING 100080,PEOPLES R CHINA
[4] ACAD SINICA,INT CTR MAT PHYS,SHENYANG 110015,PEOPLES R CHINA
[5] SHANGHAI JIAO TONG UNIV,INST CONDENSED MATTER PHYS,SHANGHAI 200030,PEOPLES R CHINA