Influence of bath composition on magnetic properties electrodeposited Co-Pt-W thin films

Effect of bath composition ([Co2+]/[Pt-N] and [WO24-], [cit(-)]) and pH on the magnetic properties of electrodeposited Co-Pt-W thin films has been investigated. Electrodeposited Co-Pt-W thin films exhibited strong perpendicular magnetic anisotropy when the ratio of [Co2+] to [Pt-IV] was 10; cathode current efficiency and perpendicular magnetic anisotropy showed little variations when [WO24-] was lower than 0.1 mol/L, but perpendicular magnetic anisotropy had strengthened when [WO24-] was over 0. 1 mol/L, which could be explained by the fact that the hydrogen evolution could produce pores as magnetic domain pinnings; citrate as complexing reagent can promote the polarization of [Co2+] and [Pt-N]. As a result, the equilibrium electrode potentials of cobalt and platinum moved to negative direction, which led to the co-deposition of Co, Pt, and W. It was also found out that the as-deposited Co-Pt-W hard magnetic thin films were very homogeneous, smooth, and had the maximum coercivity for the bath pH 8.5 and the concentration of citrate 0. 26 mol/L.