High Magnetic Field Annealing Dependent the Morphology and Microstructure of Nanocrystalline Co/Ni Bilayered Films

Co/Ni bilayered films were prepared on ITO glass by electrodeposition assisted with a magnetic field up to 0.5T aligned parallel to the electrode surface. The effect of a high magnetic field annealing up to 12T on morphology and microstructure of the post-deposited films was investigated by field emission scanning electronic microscopy (FE-SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). Grain shape and grain boundary in the Co/Ni morphology were modified dramatically when the high magnetic field was applied during the annealing process. Magnetic anisotropy appeared in the films due to the preferential orientation of fcc-CoNi alloy in comparison with a weaker orientation of hcp-Co. High magnetic field annealing favored to form a more homogeneous surface with smaller grain size and lower roughness, compared with the annealed samples obtained in the absence of magnetic field. The influencing mechanisms of high magnetic field annealing on the microstructure evolution in the Co/Ni electrodeposits are interpreted in terms of the overlapping effects: diffusion, recrystallization, grain growth and magnetic domains.