Tailoring the soft magnetic properties of CoZrTa thin film is a critical issue for enhancing magnetic recording stability for practical applications. In this work, the effect of introducing B atoms on the magnetic properties and microstructure of the CoZrTa(B) thin film was studied. The results show that the in-plane coercivity of the CoZrTaB thin film is smaller than that of the CoZrTa thin film. High-resolution transmission electron microscopy results show that the CoZrTa thin film is partially crystallized, while the CoZrTaB thin film is amorphous with a long-range disorder characteristic, indicating that the B atoms hinder crystallization and play a positive role in promoting the formation of an amorphous structure. X-ray electron spectroscopy analysis reveals that there exists a Co2B alloy in the CoZrTaB thin film, which increases the Gibbs free energy of the system and increases the energy barrier for crystallization of the film, inducing the formation of an amorphous structure. This is an important reason for obtaining good soft magnetic properties in the CoZrTaB thin film. These findings provide useful guidance for tuning the properties of the soft magnetic underlayers and also clarify the effect of amorphous structure on Co-based soft magnetic materials.
