1. Department of Electrical Engineering and Information Systems The University of Tokyo 7‐3‐1 Hongo Bunkyo‐ku Tokyo 113‐8656 Japan
2. Institute of Engineering Innovation Graduate School of Engineering The University of Tokyo 7‐3‐1 Hongo Bunkyo‐ku Tokyo 113‐8656 Japan
3. Institute for Solid State Physics The University of Tokyo 5‐1‐5 Kashiwanoha, Kashiwa‐shi Chiba 277‐8581 Japan
4. Center for Spintronics Research Network (CSRN) The University of Tokyo 7‐3‐1 Hongo Bunkyo‐ku Tokyo 113‐8656 Japan