Impact of chemical segregation on magnetic anisotropy of iron oxide films

•Iron oxide films with variable magnetic anisotropy made by magnetron sputtering.•HighresolutionX-rayspectroscopyinsightschemicalphasecomposition.•HardX-raymagnetometryextractssubstrate-freemagnetizationprofiles.•Coexistenceofferromagneticand(super)paramagneticcomponentsisproved.•Vertically elongated magnetite intrusions enhance perpendicular magnetic anisotropy. Texture-induced magnetic anisotropy is realized in iron oxide thin films deposited at room temperature onto Si(100) substrates using reactive magnetron sputtering of a Fe2O3 target. Diversities in morphology and magnetic properties are evidenced by electron microscopy and vibrating sample magnetometry. Additional insight provided by X-ray absorption spectroscopy and X-ray magnetic circular dichroism reveals fundamental differences in chemical composition and element selective magnetic properties between the films deposited in the presence of Ar and N2 reactive gas. Taking advantage of hard X-ray magnetometry, substrate-free magnetization profiles of the films were derived and deconvoluted into major magnetic components. In addition to ferromagnetic components with anisotropy defined by texture a significant contribution of (super)paramagnetic components due to rich interface structure of these nanocomposite films is observed.