Magnetoresistance of CoNiCu/Cu multilayers electrodeposited from electrolytes with different Ni Ion concentrations

Abstract

A series of CoNiCu/Cu multilayers was potentiostatically electrodeposited on strong (100) textured Cu substrates from electrolytes with different Ni concentrations. X-ray diffraction patterns showed that all studied samples exhibited a face-centered cubic structure. From scanning electron microscopy images, it was observed that the surface morphology of the films is affected by their Ni content. The compositional analysis by energy- dispersive X-ray spectroscopy demonstrated that as the Ni ion concentration in the electrolyte is increased, the Ni content of the film increases. 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 as well as GMR. As the Ni concentration in the electrolytes is increased, the AMR effect enhances, whereas the GMR effect weakens. For the 2.0 M Ni concentration, the MR behavior of multilayers converts from GMR to AMR. Furthermore, the magnetization measurements made by a vibrating sample magnetometer showed that the antiferromagnetic coupling between ferromagnetic layers weakens with increasing the Ni concentrations.