1. Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
2. Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
3. Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan
4. Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
5. School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
6. Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan
7. Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan