1. Institute of Industrial Science The University of Tokyo Meguro‐ku Tokyo 153‐8505 Japan
2. Department of Electrical Engineering and Information Systems The University of Tokyo Bunkyo‐ku Tokyo 113‐8656 Japan
3. Center for Spintronics Research Network The University of Tokyo Bunkyo‐ku Tokyo 113‐8656 Japan
4. MANA National Institute for Materials Science Tsukuba Ibaraki 305‐0044 Japan
5. JST PRESTO Kawaguchi Saitama 332‐0012 Japan