1. Advanced Research and Innovation Center, DENSO CORPORATION, Nisshin, Aichi 470-0111, Japan
2. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
3. Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
4. Center for Science and Innovation in Spintronics, Core Research Cluster, Tohoku University, Sendai 980-8577, Japan
5. Department of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
6. Tsukuba Research Center for Energy Materials Science (TREMS), University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan