Co_2CrGaフルホイスラー合金薄膜の結晶構造と磁気・電気伝導特性(薄膜)

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We investigated the structural, magnetic and electrical transport properties of Co_2CrGa full Heusler alloy films, and optimized the growth conditions, achieving stoichiometric films. The crystalline structures and the magnetic and electrical transport properties were found to depend on the film thickness, t_<CCG>. An ordered L2_1 structure was obtained for t_<CCG>≥100 nm. The saturation magnetization decreases with decreasing film thickness and vanishes below t_<CCG>=23 nm, indicating the existence of a magnetically dead layer in the vicinity of the substrates. For t_<CCG>=150 nm, the saturation magnetization is 602 emu/cm^3 (3.1 μB) at 5 K, which agrees very well with the theoretical value. The resistivity of the samples with t_<CCG>≤150 nm decreases with increasing temperature, while that with t_<CCG>=300 nm increases. By using films with t_<CCG>=100 nm and 300 nm as bottom electrodes, forming an L2_1 structure, magnetic tunnel junctions (MTJs) were also fabricated, showing 5.0% and 1.4% tunnel magnetoresistance (TMR) at RT, respectively.
社団法人日本磁気学会の論文
2005-04-01