1. Faculty of Engineering Hokkaido University Sapporo 060‐8628 Japan
2. Department of Materials Science and Engineering UC Berkeley Berkeley CA 94720 USA
3. Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
4. Department of Physics Tokyo Metropolitan University Hachioji 192‐0397 Japan
5. Graduate School of Advanced Science and Engineering Hiroshima University 1‐3‐1 Kagamiyama Higashihiroshima 739‐8526 Japan
6. Creative Research Institution Hokkaido University Kita 21, Nishi 10 Sapporo 001‐0021 Japan
7. Hitachi High‐Tech Corporation Ichige 882 Hitachinaka 312‐8504 Japan
8. Center for Crystal Science and Technology University of Yamanashi Kofu 400‐0021 Japan
9. Department of Materials Science and Engineering University of Michigan Ann Arbor MI 48109 USA