Electrodeposited NiCoFe films from electrolytes with different Fe ion concentrations

Ternary NiCoFe films, relating their magnetic and magnetoresistance properties with film composition, and the corresponding crystal structure were investigated in terms of different Fe ion concentrations in the electrolyte. The current-time transients were recorded to control the growth of proper films. The film composition by energy dispersive X-ray spectroscopy revealed that as the Fe ion concentration in the electrolyte was increased, the Fe and Co contents in the films increased and Ni content decreased. From the structural analysis by X-ray diffraction, all films had a face-centred cubic structure and, no reflection from body-centred cubic (bcc) Fe was existed in all samples due to <12 at% Fe. The saturation magnetisation increased from 865 emu/cm3 to 1080 emu/cm3 and the coercivities decreased from 60 Oe to 13 Oe with increasing Fe and Co contents and decreasing Ni content in the films. All NiCoFe films showed anisotropic magnetoresistance. The longitudinal magnetoresistance magnitudes decreased from 6.3% to 2.2% with increasing Fe and Co contents and decreasing Ni in the films while the magnitudes of transverse magnetoresistance stayed almost constant at ~5.0%. The variations in magnetic and magnetoresistive properties related to the crystal structure were attributed to the compositional changes caused by the variation of the Fe ion concentration in the electrolyte.