Cation ordering induced polarization enhancement for $PbTiO_3$-$SrTiO_3$ ferroelectric-dielectric superlattices

TL;DR

This study uses computational methods to identify cation arrangements in PbTiO3/SrTiO3 superlattices that significantly enhance ferroelectric polarization, revealing novel couplings between structural distortions and polarization.

Contribution

It introduces a large-scale computational exploration to discover cation orderings with enhanced polarization and uncovers exotic AFD-FE couplings in these superlattices.

Findings

Two special cation configurations show up to 100% increased polarization.

Exotic couplings between antiferrodistortive and ferroelectric modes are identified.

Cation motifs and couplings provide new design ideas for multifunctional perovskites.

Abstract

In this paper, an efficient computational material design approach (cluster expansion) is employed for the ferroelectric $PbTiO_3$/$SrTiO_3$ system. Via exploring a conguration space including over $3 \times 10^6$ candidates, two special cation ordered configurations: either perfect or mixed 1/1 (101) superlattice, are identified with the mostly enhanced ferroelectric polarization by up to about 100% in comparison with the (001) superlattice. Analyzing these two special configurations reveals the exotic couplings between the antiferrodistortive distortion (AFD) and ferroelectric polarization (FE) modes, e.g., tilting along x or y axis and polarization in z direction, as the origin for the best polarization property in this system. The identified cation ordering motifs and the exotic AFD-FE couplings could provide fresh ideas to design multifunctional perovskite heterostructures.