Interface Structures and Magnetic Properties of Exchanged-Coupled Co/Cu Multilayers Sputter-Grown on Ta Buffers

概要

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Interface structure-magnetic property correlations are investigated on exchange-coupled Co/Cu multilayers sputter-grown on Ta buffers. Varying the buffer thickness controls the roughness of the Co/Cu interface. The peak magnetoresistance (MR) ratio shows a marked variation with the rms roughness $ \sigma_{\text{Co/Cu}}$ from 15% at $ \sigma_{\text{Co/Cu}} \leq 0.7$ nm to very small values at $ \sigma_{\text{Co/Cu}} \geq 0.9$ nm. This variation is correlated with the surface profiles of the Ta buffers observed by atomic force microscopy, which reveals the growth of large grains in samples with $ \sigma_{\text{Co/Cu}} \geq 0.9$ nm. The reduced peak MR ratios are concomitant with the broadening of the MR profile as a function of applied in-plane field. The broadened profiles can be decomposed into the ferromagnetic and superparamagnetic components, the latter being described by the Langevin function. The reduced peak MR ratios in rough samples are accounted for by the combined effect of the increased interface roughness and orange peel effect.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2006-05-15