[1] Sejong Univ, Dept Phys, Seoul 143747, South Korea
[2] Seoul Natl Univ NS50, Sch Phys, Seoul 151747, South Korea
[3] Seoul Natl Univ NS53, Ctr Strongly Correlated Mat Res, Seoul 151, South Korea
[4] Korea Inst Sci & Technol, Future Technol Res Div, Seoul 136791, South Korea