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. • In this work we report on the structural and magnetic properties of epitaxial (111)-orientated CoFe 2 O 4 / NiFe 2 O 4 heterostructures grown by pulsed laser deposition on Al 2 O 3 (0001) substrates. • 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 amount of chemical intermixing is correlated to the strength of the exchange coupling at the interface that has implications for independent switching of layers in all-oxide spin filters. Functional oxides are a key class of materials that allows for epitaxial layering in order to combine different material properties. Epitaxial (111)-orientated CoFe 2 O 4 / NiFe 2 O 4 heterostructures were grown by pulsed laser deposition on Al 2 O 3 (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.