Electric dipole sheets in BaTiO3/BaZrO3 superlattices

We investigate two-dimensional electric dipole sheets in the superlattice made of BaTiO3 and BaZrO3 using first-principles-based Monte Carlo simulations and density functional calculations. Electric dipole domains and complex patterns are observed and complex dipole structures with various symmetries (e.g., Pma2,Cmcm, and Pmc21) 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 antivortices, are also observed, which may constitute the intermediate states that overcome the high-energy barrier of different polarization orientations previously predicted by A. I. Lebedev [Phys. Solid State 55, 1198 (2013)PSOSED1063-783410.1134/S1063783413060218]. We also show that such system possesses large electrostrictive effects that may be technologically important.