1. Department of Physics, Faculty of Science, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152
2. R & D Laboratories-1, Nippon Steel Corporation, Nakahara-ku, Kawasaki-shi, Kanagawa 211
3. Department of Physics, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko-cho, Tsukui-gun, Kanagawa 199-01
4. Department of Physics, College of General Education, Nagoya University, Furo-cho, Chigusa-ku, Nagoya 464-01