Ferroelectricity in Artificial Bicolor Oxide Superlattices

We report on the growth and properties of high quality bicolor oxide superlattices, composed of two perovskites out of BaTiO{sub 3}, CaTiO{sub 3}, and SrTiO{sub 3}. The artificially grown superlattices are structurally unique and have a macroscopically homogeneous phase, which is not feasible to recreate in bulk form. By artificial structuring, it is found that the polarization of such superlattices can be highly increased as compared to pseudo-binary ceramics with the same overall composition. Such strong enhancement in superlattice is attributed to newly-developed ionic motions of A-site cations at the hetero-interfaces due to the interfacial coupling of electrostatic and elastic interactions, which cannot be found in single phase materials.