Magnetic and magnetotransport properties in nanogranular Co/C-Co film with high magnetoresistance

巨大磁気抵抗を示すCo/C-Co薄膜の磁気的性質と磁気伝導性

境 誠司; 薬師寺 啓*; 三谷 誠司*; 菅井 勇; 高梨 弘毅*; 楢本 洋*; Avramov, P.; Lavrentiev, V.*; 鳴海 一雅; 前田 佳均

Sakai, Seiji; Yakushiji, Kei*; Mitani, Seiji*; Sugai, Isamu; Takanashi, Koki*; Naramoto, Hiroshi*; Avramov, P.; Lavrentiev, V.*; Narumi, Kazumasa; Maeda, Yoshihito

10-80%のトンネル磁気抵抗効果を示す交互蒸着法によるC-Co薄膜の磁気的性質を調べた。磁化特性の磁場及び温度への依存性について、Coナノ粒子に起因するブロッキング温度が約40Kの超常磁性が明らかになった。磁化応答は粒径分布を考慮したランジュバン関数で表され、それによりCoナノ粒子の平均粒径は3.1nm,粒径分布1nmと見積もられた。磁気的性質の測定結果に基づいて、C-Co薄膜の構造と磁気伝導現象の詳細を議論した。

Magnetic properties were investigated for the alternately deposited film of C and Co which has found to exhibit tunnel magnetoresistance (MR) of 10-80 %. Magnetic field and temperature dependences of magnetization showed typical superparamagnetic behaviors with the blocking temperature of 40 K. The magnetization curve at 300 K was well fitted by the Langevin function with the size distribution of Co particles, and the mean diameter and size distribution were evaluated to be 3.1 nm and 1 nm, respectively. Based on the magnetic properties, the detailed structure and magnetotransport properties are discussed.