[1] Korea Basic Sci Inst, Spin Engn Phys Team, Daejeon 305806, South Korea
[2] Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China
[3] Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China
[4] Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA
[5] Chungbuk Natl Univ, Dept Phys, Cheongju 28644, South Korea