1. Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama 350-0395
2. SORST, Japan Science and Technology Corporation (JST), Nihonbashi, Chuo-ku, Tokyo 103-0027
3. Hitachi Instruments Service Co., Ltd., 4-28-8 Yotsuya, Shinjuku-ku, Tokyo 160-0004
4. Department of Physics, Tokyo Institute of Technology, Ohokayama, Meguro-ku, Tokyo 152-8551
5. Department of Physics and Istituto Nazionale per la Fisica della Materia,
University of Bologna, Viale B. Pichat 6/2, 40127 Bologna, Italy
6. Department of Applied Chemistry, University of Tokyo, Tokyo 113-8656
7. Department of Advanced Materials Science, School of Frontier Sciences, University of Tokyo, Tokyo 113-0033
8. Department of Material Science, Japan Atomic Energy Research Institute, Tokai, Naka-gun, Ibaraki 319-1195