Structural and energetic properties of domains in PbTiO 3 /SrTiO 3 superlattices from first principles

Abstract

We report first-principles calculations, within the density functional theory, on the structural and energetic properties of 180 ∘ stripe domains in (PbTiO 3 ) n /(SrTiO 3 ) n superlattices. For the explored periodicities (n=3 and 6), we find that the polydomain structures compete in energy with the monodomain phases. Our results suggest the progressive transition, as a function of n , from a strong to a weak electrostatic coupling regime between the SrTiO 3 and PbTiO 3 layers. Structurally, they display continuous rotation of polarization connecting 180 ∘ domains. A large offset between [100] atomic rows across the domain wall and huge strain gradients are observed. The domain wall energy is very isotropic, depending very weakly on the stripe orientation.