[1] Huazhong Univ Sci & Technol, Sch Phys, Wuhan 430074, Peoples R China
[2] Huazhong Univ Sci & Technol, Wuhan Natl Magnet Field Ctr, Wuhan 430074, Peoples R China
[3] Natl Taiwan Univ, Dept Phys, Taipei 10617, Taiwan
[4] Natl Taiwan Univ, Inst Appl Phys, Taipei 10617, Taiwan