1. Department of Physics, Faculty of Science, Kobe University, Kobe 657-8501
2. Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397
3. Department of Mathematical and Natural Sciences, Faculty of the Integrated Arts and Sciences, The University of Tokushima, Tokushima 770-8502
4. Department of Materials Science and Technology, Faculty of Engineering, Niigata University, Niigata 950-2181
5. Department of Physics, Okayama University, Okayama 700-8530