In this Rapid Communication, an efficient computational material design approach (cluster expansion) is employed for the ferroelectric ${\mathrm{PbTiO}}_3/{\mathrm{SrTiO}}_3$ system. Via exploring a configuration space including over $3\times {10}^6$ 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., ${\mathrm{AFD}}_x\text{−}{\mathrm{FE}}_z$ and ${\mathrm{AFD}}_{xy}\text{−}{\mathrm{FE}}_z$), 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.

• Received 3 December 2013
• Revised 19 January 2015

DOI:https://doi.org/10.1103/PhysRevB.91.081301