1. Department of Physics, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
2. Bio–AFM Frontier Research Center, College of Science & Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
3. Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Sanban-cho, Chiyoda-ku, Tokyo 102-0075, Japan.
4. Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
5. Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.