1. Research Institute for Electronic Science Hokkaido University N20W10 Kita Sapporo 001‐0020 Japan
2. Graduate School of Information Science and Technology Hokkaido University N14W9 Kita Sapporo 060‐0814 Japan
3. Institute of Engineering Innovation The University of Tokyo 2‐11‐16 Yayoi, Bunkyo Tokyo 113‐8656 Japan
4. Inorganic Functional Materials Research Institute National Institute of Advanced Industrial Science and Technology (AIST‐Chubu) Anagahora 2266‐98, Shimoshidami, Moriyama Nagoya 463‐8560 Japan
5. Department of Electrophysics and Center for Emergent Functional Matter Science National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan
6. Department of Electrophysics National Chiao Tung University Hsinchu 30010 Taiwan
7. Department of Physics Keio University 3‐14‐1 Hiyoshi, Kohoku‐ku Yokohama 223‐8522 Japan