1. Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
2. International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
3. Department of Applied Physics, Osaka University, Osaka 565-0871, Japan
4. Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
5. Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8585, Japan
6. SANKEN, Osaka University, Ibaraki, Osaka 567-0047, Japan
7. Spintronics Research Network Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Osaka 565-0871, Japan
8. Center for Spintronics Research Network, Osaka University, Toyonaka, Osaka 560-8531, Japan