Dependence of Magnetoresistance in Electrodeposited CoNiCu/Cu Multilayers on Ni Composition

A series of CoNiCu/Cu multilayers was potentiostatically electrodeposited on strong (100) textured Cu substrates from the electrolytes with different Ni concentrations. The x-ray diffraction (XRD) data showed that all studied samples exhibited a face centred cubic (fcc) structure. According to scanning electron microscopy (SEM) images, the surface morphology of the films is affected by their Ni content. The chemical analysis by energy dispersive x-ray spectroscopy (EDX) demonstrates that as the Ni ion concentration in the electrolyte is increased, the Ni content of the film increases while the Co and Cu contents decrease. Magnetoresistance (MR) measurements were carried out at room temperature in the magnetic fields of +/- 12 kOe. The samples grown from the electrolytes with the Ni concentration of up to 0.3 M exhibited giant magnetoresistance (GMR). For the samples grown from 0.3 M Ni, anisotropic magnetoresistance (AMR) begins to appear. The GMR decreased with increasing Ni concentration and the AMR appeared. For the 2.0 M Ni concentration, MR converted from GMR to AMR. Furthermore, the magnetization measurements made by a vibrating sample magnetometer (VSM) showed that the antiferromagnetic coupling between ferromagnetic layers weakened with increasing the Ni concentrations.