1. Department of Applied Science Okayama University of Science Okayama 700‐0005 Japan
2. Institute of Applied Physics Graduate School of Pure and Applied Sciences University of Tsukuba Tsukuba Ibaraki 305‐8573 Japan
3. Department of Physics Graduate School of Science Tohoku University Sendai 980‐8578 Japan
4. Advanced Institute for Materials Research Tohoku University Sendai 980‐8577 Japan
5. Center for Spintronics Research Network Tohoku University Sendai 980‐8577 Japan
6. Precursory Research for Embryonic Science and Technology (PRESTO) Japan Science and Technology Agency (JST) Tokyo 102‐0076 Japan
7. Graduate School of Engineering Science Osaka University, 1‐3 Machikaneyama Toyonaka 560‐8531 Japan
8. Department of Chemistry Graduate School of Science Osaka University 1‐1 Machikaneyama Toyonaka Osaka 560‐0043 Japan
9. Institute for Materials Research Tohoku University Katahira 2‐1‐1 Sendai 980‐8577 Japan
10. Department of Materials Science and Engineering Johns Hopkins University Baltimore MD 21218 USA
11. Mathematical Institute Graduate School of Science Tohoku University Sendai 980‐8578 Japan