1. Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea.
2. Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea.
3. Center for Theoretical Physics (CTP), Seoul National University, Seoul 08826, Republic of Korea.
4. Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea.
5. Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.