Interface control by chemical and dimensional matching in an oxide heterostructure

Interfaces between different materials underpin both new scientific phenomena, such as the emergent behaviour at oxide interfaces, and key technologies, such as that of the transistor. Control of the interfaces between materials with the same crystal structures but different chemical compositions is possible in many materials classes, but less progress has been made for oxide materials with different crystal structures. We show that dynamical self-organization during growth can create a coherent interface between the perovskite and fluorite oxide structures, which are based on different structural motifs, if an appropriate choice of cations is made to enable this restructuring. The integration of calculation with experimental observation reveals that the interface differs from both the bulk components and identifies the chemical bonding requirements to connect distinct oxide structures. The behaviour of heterostructures, crucial in nanodevices, largely depends on interfacial phenomena. These have proven difficult to control when the different materials adopt distinct crystal structures. Now, a coherent interface between perovskite and fluorite has been achieved that relies in particular on the coordination flexibility of judiciously chosen metal cations.