Microstructure, magnetic properties and the giant magnetoimpedance effect of amorphous CoSiB thin films deposited by different preparation methods

Abstract

Controlling the film thickness and soft magnetic properties are the two key factors for giant magnetoimpedance effect (GMI). In this paper, we reported that the ion beam assisted deposition (IBAD) is useful for preparing the GMI materials thin films. The CoSiB thin films with a thickness of a few micron prepared by IBAD shows a very superior ability to combine with the substrate compared with DC and RF sputtering method. Meanwhile, the thick CoSiB thin film by IBAD method also exhibits a good soft magnetic property, but the grown CoSiB films by RF sputtering showed thickness-driven spin orientation behavior in thick CoSiB films leading to the deterioration of its soft magnetic properties. Thus, a Ti layer was introduced to eliminate thickness-driven magnetic behavior in thick FeNi films and thereby preserve their magnetic softness. Furthermore, we found that the GMI effect of CoSiB films prepared by IBAD is stronger than that of magnetron sputtering. Especially, an excellent GMI phase effect in a low frequency range was observed in the CoSiB film prepared by IBAD, which was beneficial for high sensitive magnetic sensor design. In the end, x-ray diffraction and x-ray photoelectron spectroscopy analyses suggest that all the thin films prepared by the sputtering or IBAD method show the metallic glasses structure, thus the origin of the difference in magnetism is may be due to their different short-order structure.