Cation ordering induced polarization enhancement for PbTiO3-SrTiO3 ferroelectric-dielectric superlattices

In this Rapid Communication, an efficient computational material design approach (cluster expansion) is employed for the ferroelectric PbTiO3/SrTiO3 system. Via exploring a configuration space including over 3 x 10(6) candidates, two special cation ordered configurations-either perfect or mixed 1/1 (011) superlattice-are identified with the mostly enhanced ferroelectric polarization by up to about 95% in comparison with the (001) superlattice. We find that the exotic couplings between the antiferrodistortive (AFD) and ferroelectric (FE) modes (e.g., AFD(x)-FEz and AFD(xy)-FEz), which is absent from the PTO and STO, as the origin for the best polarization property of the two superlattices. This understanding should provide fresh ideas to design multifunctional perovskite heterostructures.