1. Department of Applied Physics, Nagoya University, Nagoya 464-8603, Japan
2. The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
3. Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
4. Cross-Correlated Materials Research Group (CMRG) and Correlated Electron Research Group (CERG), RIKEN-ASI, Wako, Saitama 351-0198, Japan