1. Department of Electrical Engineering, Graduate School of Engineering, Tohoku University, 6-6-04 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan
2. Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
3. Toei Scientific Industrial Co., Ltd, 1-101-60 Medeshimadai, Natori, Miyagi 981-1251, Japan
4. Department of Electrical and Electronic Engineering, Faculty of Engineering, Tohoku Gakuin University, 1-13-1 Chuo, Tagajo, Miyagi 985-8537, Japan
5. Division of Biomedical Engineering for Diagnosis and Treatment, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan