Effect of sputtering pressure on microstructure and magnetic properties of amorphous FeCoSiB films

The effects of argon pressure on the microstructure and magnetic properties of the sputtered FeCoSiB amorphous films were investigated. At low deposition pressure the samples show flat and dense surface, while those at higher pressure show columnar growth with rough surface. The formation of the columnar grains results in the perpendicular magnetic anisotropy due to the shape anisotropy. Stripe magnetic domains were observed in the latter samples. Both the magnetic contrast in magnetic force microscope images and the coercivity of FeCoSiB films increase first and then decrease with the increasing of the sputtering pressure. It is suggested that the columnar grains introduce shape anisotropy which plays an important role in tuning the magnetic behaviors of the FeCoSiB films with the sputtering pressure.