1. Electrical and Electronic Engineering and Information System The University of Tokyo 7‐3‐1 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