1. Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
2. Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
3. Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
4. Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
5. Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea