Overcoming the limits of exchange bias effect in the magnetic thin films by introducing nanostructured internal interfaces

Abstract

Phase mixture single layer film with 3-dimensional spatial distribution of internal interfaces between ferromagnetic and antiferromagnetic nanoclusters was achieved through the inhomogeneous distribution of oxygen atoms within the ferromagnetic transition metal thin film layer. In the present work, enhanced exchange bias properties of phase mixture single layer film including both exchange and super-exchange couplings within the body of the single layer were investigated under various conditions. The film exhibited same exchange bias field regardless of the layer thickness, which violates the known relationship of inverse proportionality between the exchange bias field and the thickness of the magnetic layer in the conventional ferromagnet/antiferromagnet bilayers systems. Furthermore, it was found that the exchange bias could be set in any direction with respect to the film surface, removing the restriction by the magnetic shape anisotropy of the thin film structure. Low blocking temperature of the phase mixture single layer film could also be overcome with an additional neighboring antiferromagnet layer.