1. Department of Electrical Engineering and Information Systems School of Engineering The University of Tokyo 7‐3‐1 Hongo, Bunkyo‐ku Tokyo 113‐8656 Japan
2. Center for Emergent Matter Science RIKEN 2‐1 Hirosawa Wako Saitama 351‐0198 Japan
3. Thin‐Film Device Laboratory RIKEN 2‐1 Hirosawa Wako Saitama 351‐0198 Japan