Magnetic properties of nanocrystalline iron group thin film alloys electrodeposited from sulfate and chloride baths

Systematic studies of iron group binary (NiCo and CoFe) and ternary (CoNiFe) thin film alloys relating their magnetic properties with film composition, grain size and the corresponding crystal structure were investigated. Anions influence current efficiencies, magnetic properties, surface morphology and phases of electrodeposited films. Higher current efficiencies in chloride baths compared to sulfate baths were observed for CoFe, NiCo and CoNiFe alloys. The higher deposition current efficiencies in chloride baths were attributed to a catalytic effect. Anion types in CoFe and CoNiFe thin film alloys influenced the microstructures and the resulting magnetic properties (coercivity and squareness). The microstructures of NiCo alloys depend on the deposit Co contents rather than anion types. The surface morphologies of CoFe, NiCo and CoNiFe thin films were independent of anion types. CoFe deposits exhibited relatively smooth surface morphology and turned into fine crystallites with increasing solution Fe⁺² concentration. NiCo deposits showed very smooth surface morphology. CoNiFe deposits had the surface morphology of polyhedral crystallites. The deposit Fe content in CoFe electrodeposits linearly increased with increasing solution Fe⁺² concentration for both chloride and sulfate baths. Similar linear behavior of deposit Co contents was observed in NiCo electrodeposits.