1. Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
2. Department of Quantum Materials, Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
3. Department of Physics, Faculty of Science and Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
4. CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
5. Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, U.S.A.