Magnetic Field Effects on Surface Morphology and Magnetic Properties of Co–Ni–N Thin Films Prepared by Electrodeposition

Abstract

The surface morphology and magnetic properties of Co–Ni–N thin films electrodeposited under an external magnetic field were investigated. The films were electroplated on Al substrates using the same electrodeposition parameters (temperature and pH) for all experiments, with an external magnetic field of 107 Oe applied to the cathode surface. The films were compared with similar samples obtained in the absences of magnetic field. The magneto-induced modifications in the Co–Ni–N morphology can be explained by the specific local convection of ions at the interface cathode-electrolyte, which promotes changes both in the electrical charge of the double layer and in the thickness of the diffusion layer. From the magnetic measurements, we found that the coercivity varied between H c =(14÷27) kA/m depending on the direction of the applied magnetic field and on the sodium nitrate content in the plating bath. It was observed that an induced anisotropy appeared in the Co–Ni–N films due to the preferential orientation of the easy axis of magnetization in the magnetic field direction. In addition, the Co–Ni–N alloy films showed good magnetic property, which is considered that not only the smaller grain size of the films, but also more uniform surface of the films than that deposited in absence of applied magnetic field.