Large tunnel magnetoresistance in Co-evaporated C60-Co thin films

共蒸着法で作製したC60-Co薄膜の巨大トンネル磁気抵抗効果

境 誠司; 菅井 勇; 三谷 誠司*; 松本 吉弘; 高梨 弘毅; 楢本 洋*; Avramov, P.; 岡安 悟  ; 前田 佳均

Sakai, Seiji; Sugai, Isamu; Mitani, Seiji*; Matsumoto, Yoshihiro; Takanashi, Koki; Naramoto, Hiroshi*; Avramov, P.; Okayasu, Satoru; Maeda, Yoshihito

Bias-voltage dependences of the magnetotransport properties were investigated for the co-deposited C60-Co films with a nano-granular structure. The electrical resistivity near zero bias exhibited a characteristic temperature dependence to nanogranular systems. It is found that the MR behaves a nonmonotionic bias-voltage dependence. MR shows significant decrease and increase with V-increase in the low and high-bias regions separated by a certain V of a few mV per a Co nanoparticle. The maximum MR observed in the low/high bias regions are 80% and 90%. The MR effect observed for the C60-Co films is, as far as we know, the largest one in granular systems, and is significant larger than MR of 50% expected under the condition of complete spin-polarization. The bias-dependent MR change is suggested to be associated with the charging effect of Co nanoparticles.