1. Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.
2. Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan.
3. The Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan.
4. Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan.
5. RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan.
6. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
7. Condensed Matter Research Center and Photon Factory, Institute of Materials Structure Science, KEK, Tsukuba 305-0801, Japan.
8. Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan.
9. PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.