Morphology and magnetic properties of electroplated Co-rich Co-Zn thin films

This work explores the microstructure and magnetic properties of electrodeposited Co-Zn thin films. Using pulse-reverse electroplating technique, Co-rich Co-Zn films are deposited 0.4–1.9 μm thick from aqueous sulfate-based baths at low temperature (55°C). The influence of current density (25–100 mA/cm²) and electrolyte Zn concentration (0–0.28 M) on the microstructure and magnetic properties are investigated. All of the Co-Zn films exhibit higher out-of-plane coercivity, as compared to in-plane. With increasing current density, the out-of-plane coercivity decreases from 50 to 40 kA/m (628–500 Oe). The influence of the Zn concentration in the electrolyte is more pronounced, affecting the grain size, film composition, and magnetic properties. The best magnetic properties were obtained from a bath with 0.21 M Zn and an average current density of 25 mA/cm², resulting in a Co₉₇Zn₃ composition and an out-of-plane coercivity of 92 kA/m (1,160 Oe).