1. Department of Physics, Sophia University, Kioi-cho, Chiyoda-ku, Tokyo 102-8554
2. Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551
3. Department of Chemistry, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551
4. Institute for Solid State Physics, University of Tokyo, Roppongi, Minato-ku, Tokyo 106-8666