[1] Pohang Univ Sci & Technol, Dept Phys, Pohang 790784, Kyungbuk, South Korea
[2] Pohang Univ Sci & Technol, Electron Spin Sci Ctr, Pohang 790784, Kyungbuk, South Korea
[3] Korea Inst Sci & Technol, Nano Device Res Ctr, Seoul 130650, South Korea
[4] Catholic Univ Korea, Dept Phys, Puchon 420743, South Korea
[5] Chonbuk Natl Univ, Dept Phys, Jeonju 561756, South Korea