Electrodeposition of soft, high moment Co–Fe–Ni thin films

The electrodeposition of Co–Fe–Ni films from electrolytes without additives and their magnetic and structural properties in the as-deposited and vacuum annealed states are reported. Co52Fe26Ni22 alloy films exhibit a saturation magnetization Bs of 20 kG, coercivity Hc around 1 Oe, resistivity of 22 μΩ cm and saturation magnetostriction of about 10−6. Crystalline structure from bcc to fcc changes with increasing Ni content; films with best soft magnetic properties are obtained when bcc and fcc structures coexist. Varying electrolyte formulation or using pulse plating, the deposition parameters which yield optimum soft magnetic properties vary, but alloy composition and crystalline structure of optimum films are unchanged. dc plated films exhibit Ni enrichment at the interface in a region of about 1 μm thickness. Easy axis annealing in a vacuum of 10−7 Torr at 200–280 °C for 30 min decreases Hc and slightly decreases the anisotropy field. Annealing, however, does not change Bs, crystalline structure or lattice parameters, demonstrating stability of the film structure when subjected to typical device processing temperature cycles.