1. Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
2. Center for Advanced High Magnetic Field Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
3. Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
4. Low Temperature Center, Osaka University, Toyonaka, Osaka 560-0043, Japan
5. Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan
6. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
7. RIKEN, Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
8. Tokyo College, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan