Effect of domain wall on the dielectric properties of the BaTiO3/SrTiO3 superlattices

Based on a phenomenological thermodynamical theory, the effect of the domain wall on the dielectric properties of the polydomain BaTiO3/SrTiO3 superlattices with 180° electric domains in the BaTiO3 layer is investigated. Theoretical analysis indicates that complete polarization suppression and the largest dielectric response take place at approximately 72% and 53% of the critical volume fraction of the SrTiO3 layer for the domain wall energy parameter A=3×107 and 5×107, respectively. The dielectric properties largely depend on both the volume fraction of the SrTiO3 layer and the domain wall energy parameter. Moreover, the gigantic dielectric response which occurs in single-domain BaTiO3/SrTiO3 superlattices cannot appear due to the 180° polydomain state in the BaTiO3 layer, which is in agreement with the previous prediction. The high domain wall energy parameter results in the stabilization of the paraelectric state in the BaTiO3 layer, however, the enhancement of the domain wall energy parameter within a certain scale increases the dielectric properties greatly.