1. Department of Material Science, Graduate School of Science and Technology, Kobe University, Nada, Kobe 657
2. Department of Physics, Faculty of Science, Kobe University, Nada, Kobe 657
3. Faculty of Engineering, Himeji Institute of Technology, Shosya, Himeji 671-22
4. Faculty of Engineering, Ehime University, Bunkyo, Matsuyama 790