[1] Tohoku Univ, Grad Sch Engn, Dept Appl Phys, Sendai 9808579, Japan
[2] Tohoku Univ, Grad Sch Engn, Dept Met Sci & Mat Proc, Sendai 9808579, Japan
[3] Tohoku Univ, Grad Sch Engn, Dept Elect Engn, Sendai 9808579, Japan
[4] Tohoku Univ, Ctr Sci & Innovat Spintron Core Res Cluster, Org Adv Studies, Sendai 9808577, Japan