Electrodeposition of ferromagnetic materials for magnetic recording media: Syntesis, structural and magnetic properties

In this study, CoNiFe and CoNiFe-Cu alloy films were grown on polycrystalline Ti (hcp) substrates from electrolytes containing their ions by the electrodeposition technique. The properties were investigated as a function of the deposition potentials, the film thickness, the electrolyte pH and the Cu concentration. The deposition potentials of films vs saturated calomel electrode (SCE) were determined as -1.4 V by the cyclic voltammetry (CV) method. During deposition, the current-time transients were recorded to investigate growth mechanisms of films. CoNiFe and CoNiFe-Cu films were found to have different growth mechanisms from each other. The structural characterisations of CoNiFe films without Cu and with Cu produced under different deposition conditions such as the Cu concentration, the deposition potential, the film thickness was studied using X-ray diffraction (XRD). In XRD patterns of films, the reflection peaks came from (111), (200), (220) and (311) planes of face centered cubic (fcc) structure were clearly observed. By considering different parameters, the magnetic properties of samples were measured by the vibrating sample magnetometer (VSM) technique. CoNiFe-Cu films grown from electrolyte containing 0,005 M Cu ion were found to have the highest magnetization value (Ms=5195 emu/cm3) and CoNiFe film grown at -1,8 V had the lowest coercivity (Hc=25,5 Oe). The magnetoresistance (MR) measurements of the samples were carried out by the van der Pauw technique. All films, except for films produced from the electrolytes having 0,03 and 0,04 M Cu ion concentration showed anisotropic magnetoresistance (AMR) behaviour. It was observed that MR ratios of both CoNiFe and CoNiFe-Cu films were significantly affected by the deposition conditions.