Exchange bias in FexZn1−xF2/Co bilayers

Abstract

The exchange bias (HE) was measured in FexZn1−xF2/Co bilayers grown on MgO (100) with and without a 1.0 nm layer of pure FeF2 at the interface between the FexZn1−xF2 and the Co layers. For x=0.83 samples with an additional 1.0 nm FeF2 interface layer HE increases by 65% when compared to the FeF2/Co bilayer. The FeF2 interface layer also causes a significant HE to appear for x<0.5. This enhancement of HE with an FeF2 interlayer cannot be explained by simply scaling the exchange bias with the Fe concentration. Presumably this is due to the formation of domain states inside the dilute antiferromagnetic film, and the pure interface layer increases the coupling between the ferromagnet and the antiferromagnet.