1. RIKEN Center for Emergent Matter Science (CEMS) , Wako , Japan
2. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee , United States
3. Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology (KIT) , Karlsruhe , Germany
4. Research and Development Group, Hitachi Ltd. , Hatoyama, Saitama , Japan
5. Research Institute for Science and Technology, Kogakuin University , Hachioji, Tokyo , Japan
6. Department of Advanced Materials Science, University of Tokyo , Kashiwa , Japan
7. Department of Applied Physics, University of Tokyo , Tokyo , Japan
8. Tokyo College, University of Tokyo , Tokyo , Japan