1. Advanced
Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
2. RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
3. Central
Research Laboratory, Hitachi, Ltd., Saitama 350-0395, Japan
4. Department
of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
5. PRESTO, Japan Science and Technology Agency, Tokyo 102-0076, Japan