Misfit accommodation in oxide thin film heterostructures

Abstract

Complex oxides are of intense interest due to their diverse properties, such as colossal magnetoresistance and superconductivity. Their complexity arises not only from the number of constituent elements, but also from their tolerance of non-stoichiometry and the structural complexity of these perovskite-based materials, e.g. the distortions and rotations of the oxygen octahedra surrounding the B-site cation. For these reasons, misfit accommodation in these materials is far more complex than in simpler materials, and can involve several different mechanisms simultaneously. In some cases, interfaces can be free from any misfit dislocations, lattice mismatch being accommodated via incorporation of oxygen vacancies, which take an ordered periodic arrangement. Interfaces may also present a perturbation to the octahedral rotations that can dramatically affect properties, not just close to the interface but through the entire film. In oxygen ion conducting materials, the oxygen sublattice may even melt in some situations.