Interfacial coupling effect of Cr2O3 on the magnetic properties of Fe72Ga28 thin films

Abstract

Here it is investigated the effect of the antiferromagnet Cr2O3 on the magnetic properties of ferromagnetic Fe72Ga28 thin films. Although Fe72Ga28 layers have their magnetization almost in the sample plane, the interfacial coupling with Cr2O3 that has perpendicular magnetic moments enables to turn the Fe72Ga28 magnetization direction into the out of plane (OOP) direction. Cr2O3 has been obtained from Cr oxidation, whereas Fe72Ga28 has been deposited on top of it by sputtering in the ballistic regime. Although a uniaxial in-plane magnetic anisotropy is expected for Fe72Ga28 thickness above 100 nm, the interfacial coupling with Cr2O3 prevents this anisotropy. The formation of stripe domains in Fe72Ga28 above a critical thickness reveals the enhancement of the out of plane component of the Fe72Ga28 magnetization with respect to uncoupled layers. Due to the interface coupling, the Fe72Ga28 magnetization turns into the out-of-plane direction as its thickness is gradually reduced, and a perpendicular magnetic anisotropy of 3.4·106 erg·cm− 3 is inferred from experimental results. Eventually, the coupling between Cr2O3 and Fe72Ga28 promotes an exchange-bias effect that has been well fitted by means of the random field model.