Tuning microstructure and magnetic properties of electrodeposited CoNiP films by high magnetic field annealing

• High magnetic field annealing accelerated phase transformation from γ to ε.
• High magnetic field annealing enhanced preferred hcp-(002) orientation.
• High magnetic field annealing decreased particle size, roughness and coercivity.
• High magnetic field annealing increased the saturation and remanent magnetization.

A high magnetic field (up to 12 T) has been used to anneal 2.6-µm-thick Co50Ni40P10 films formed by pulse electrodeposition. The effects of high magnetic field annealing on the microstructure and magnetic properties of CoNiP thin films have been investigated. It was found that a high magnetic field accelerated a phase transformation from fcc to hcp and enhanced the preferred hcp-(002) orientation during annealing. Compared with the films annealed without a magnetic field, annealing at 12 T decreased the surface particle size, roughness, and coercivity, but increased the saturation magnetization and remanent magnetization of CoNiP films. The out-of-plane coercivity was higher than that the in-plane for the as-deposited films. After annealing without a magnetic field, the out-of-plane coercivity was equal to that of the in-plane. However, the out-of-plane coercivity was higher than that of the in-plane when annealing at 12 T. These results indicate that high magnetic field annealing is an effective method for tuning the microstructure and magnetic properties of thin films.