1. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
2. Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
3. Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
4. Riken Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
5. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
6. Department of Applied Physics, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan