1. Department of Physics and Astronomy, Kagoshima University, Kagoshima 890-0065, Japan
2. Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
3. Research Institute for Engineering and Technology, Tohoku Gakuin University, Tagajo, Miyagi 985-8537, Japan
4. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
5. Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
6. Center for Science and Innovation in Spintronics, Tohoku University, Sendai 980-8577, Japan