1. International Center for Young Scientists (ICYS) and WPI International Center for Materials Nanoarchitectonics (WPI‐MANA) National Institute for Materials Science (NIMS) Tsukuba Ibaraki 305‐0044 Japan
2. Department of Materials Science and Engineering National Taiwan University Taipei 10617 Taiwan
3. Department of Electrophysics National Chiao Tung University Hsinchu 30010 Taiwan
4. Department of Chemistry School of Science The University of Tokyo Tokyo 113‐0033 Japan
5. Research Center for Science and Technology Tokyo University of Science Chiba 278‐8510 Japan
6. Center of Atomic Initiative for New Materials (AI‐MAT) National Taiwan University Taipei 10617 Taiwan