Correlation Between Structural Imperfection and Giant Magnetoresistance in Electrodeposited Co/Cu Multilayers

The effect of structural imperfection on the giant magnetoresistance (GMR) of electrodeposited Co/Cu multilayer films was examined. The Co/Cu multilayers were grown on (100)-textured Cu seed layers on Si(100). Transmission electron microscopy revealed that the epitaxial growth of the Co/Cu multilayers results in columnar grains with an average width of 40-60 nm. The multilayer structure is significantly perturbed by grain boundary grooving. The perturbation gives rise to strong magnetostatic coupling between neighboring magnetic layers, which overwhelms the desired antiferromagnetic exchange coupling required for large GMR.