1. Institute for Materials Research, Tohoku University 1 , Sendai 980-8577, Japan
2. Department of Materials Science, Graduate school of Engineering, Tohoku University 2 , Sendai 980-8579, Japan
3. Frontier Research Institute for Interdisciplinary Sciences, Tohoku University 3 , Sendai 980-0845, Japan
4. Research Institute of Electrical Communication, Tohoku University 4 , Sendai 980-8577, Japan
5. Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science 5 , Tsukuba 305-0047, Japan
6. Institut für Physik, Johannes Gutenberg-Universität Mainz 6 , Staudingerweg 7, 55128 Mainz, Germany
7. Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University 7 , Sendai 980-8577, Japan
8. Advanced Science Research Center, Japan Atomic Energy Agency 8 , Tokai 319-1195, Japan