[1] Univ Seoul, Dept Phys, Seoul 130743, South Korea
[2] Seoul Natl Univ, Ctr Strongly Correlated Mat Res, Sch Phys, Seoul 151742, South Korea
[3] Pohang Univ Sci & Technol, Natl Creat Res Initiat Ctr Superconduct, Pohang 790784, South Korea
[4] Pohang Univ Sci & Technol, Dept Phys, Pohang 790784, South Korea
[5] Univ Maryland, Dept Phys, College Pk, MD 20742 USA
[6] Sogang Univ, Dept Phys, Seoul 121742, South Korea