The effects of interfacial interactions between Fe–O and Fe–Si induced by ion-beam bombardment on the magnetic properties of Si-oxide/Fe bilayers

• Si capping layer was deposited on Fe layer with O2/Ar ion beam bombardment.
• Structure deformation and grain re-orientation was observed after bombardment.
• FeO, Fe2O3, SiO2, and FeSi were formed in the interface, as proved by XPS.
• The interface layer resulted in magnetic coercivity enhancement at low temperature.
• Fe–O changed to antiferromagnetic at 10 K, establishing exchange coupling with Fe.

Si/Fe and SiO2/Fe thin-film heterostructures are commonly seen in magnetic multilayer devices, whose magnetic properties are strongly influenced by intermixing at the interfaces. In this paper, Si-oxide/Fe bilayers were formed by depositing Si on Fe with in situ O2/Ar ion-beam bombardment during the Si deposition. The surface oxidation conditions were altered by applying different O2/Ar ratios (0–41%) in the ion-beam. The surface and cross-sectional morphologies, and the crystalline structures were characterized by transmission electron microscopy. The formation of Fe–O, Fe–Si and Si–O bonds at the interface of the O2/Ar ion-beam bombarded Si-oxide/Fe bilayers was evidenced by X-ray photoemission spectra. FeO, Fe3O4 and Fe2O3 at the interface resulted in a marked increase in the magnetic coercivity at low temperatures, as characterized by magnetometry.