Electric dipole sheets in BaTiO$_{3}$/BaZrO$_{3}$ superlattices

TL;DR

This study explores complex two-dimensional electric dipole patterns in BaTiO₃/BaZrO₃ superlattices, revealing various symmetries, vortex structures, and significant electrostrictive effects through first-principles simulations.

Contribution

It provides the first detailed analysis of complex dipole structures and their symmetries in BaTiO₃/BaZrO₃ superlattices using combined Monte-Carlo and density functional methods.

Findings

Identification of multiple dipole symmetries close in energy to the ferroelectric ground state.

Observation of vortex and anti-vortex dipole patterns.

Large electrostrictive effects in the superlattice system.

Abstract

We investigate two-dimensional electric dipole sheets in the superlattice made of BaTiO$_{3}$ and BaZrO$_{3}$ using first-principles-based Monte-Carlo simulations and density functional calculations. Electric dipole domains and complex patterns are observed and the complex dipole structures with various symmetries (e.g. Pma2, Cmcm and Pmc2_{1}) are further confirmed by density functional calculations, which are found to be almost degenerate in energy with the ferroelectric ground state of the Amm2 symmetry, therefore strongly resembling magnetic sheets. More complex dipole patterns, including vortices and anti-vortices, are also observed, which may constitute the intermediate states that overcome the high energy barrier of different polarization orientations previously predicted by Lebedev\onlinecite{Lebedev2013}. We also show that such system possesses large electrostrictive effects that may be technologically important.