1. Department of Physics, 120 Willamette Hall, 1371 E 13th Avenue, Eugene, Oregon 97403, USA
2. Research and Development Group, Hitachi Ltd., Hatoyama 350-0321, Japan
3. RIKEN Center for Emergent Matter Science (CEMS), Hatoyama 350-0321, Japan
4. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan