New developments in artificially layered ferroelectric oxide superlattices

Artifi cially layered superlattices of oxide materials have been intensely investigated for some
time, but continue to reveal new potential as a route to advanced functional materials. As
well as considering electrostatics and strain, a more complete picture of the interfaces in
these systems also needs to incorporate the possibility of additional structural distortions,
electronic redistributions, and complex polarization domain structures. Here we focus on
superlattices composed of two perovskite oxide materials, where one is a ferroelectric, and
discuss the important interactions between the component materials that determine the
behavior of the new artifi cial material. We discuss interfaces both with and without electronic
screening. The fi rst class of interface contains technologically relevant ultrathin ferroelectric
capacitors and the more recently studied ferroelectric-metal superlattices. In these systems,
the infl uence of the ferroelectric polarization decreases rapidly with distance from the interface.
By contrast, in systems where the materials adjacent to the ferroelectric layers are dielectrics,
the polarization of the ferroelectric layer infl uences the properties of the adjacent layers over
a much longer distance, setting the stage for fascinating competition between the properties
of the combined materials.