Magnetic interactions in CoFe2O4 / NiFe2O4 heterostructures

Functional oxides are a key class of materials that allows for epitaxial layering in order to combine different material properties. Epitaxial (111)-orientated CoFe2O4 / NiFe2O4 heterostructures were grown by pulsed laser deposition on Al2O3(0001) substrates and their structural and magnetic properties investigated. Whilst X-ray diffraction and electron microscopy demonstrate a single high quality coherent epitaxial film in the growth direction, chemical mapping by EDX and polarised neutron reflectivity analysis confirms chemical intermixing of Co and Ni ions across the interface. The chemical intermixing correlates to the strength of the exchange coupling at the interface that has implications for independent switching of layers in all-oxide spin filters.