1. RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
2. Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue,
Madison, Wisconsin 53706, United States
3. Electron Microscopy Group, National Institute for Materials Science, Tsukuba 305-0044,
Japan
4. Department of Applied
Physics
and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan