Swirling topological textures of polarization in bulk relaxor ferroelectrics

TL;DR

This paper reveals swirling topological polarization textures, including vortices like merons, in bulk relaxor ferroelectrics, linking nanoscale polarization correlations to chemical heterogeneities and dielectric relaxation mechanisms.

Contribution

It introduces a structural refinement framework that integrates experimental data to identify nanoscale polarization correlations and topological textures in relaxor ferroelectrics.

Findings

Identification of swirling polarization textures with vortices.

Link between vortex locations and compositional heterogeneities.

Correlation of topological textures with dielectric relaxation mechanisms.

Abstract

A complete understanding of the mechanisms for dielectric relaxation in relaxor ferroelectrics remains elusive. We used a structural refinement framework that integrates several types of experimental data to identify the nanoscale correlations of polarization and their relationship to the underlying chemistry in the classic relaxor system PbMg1/3Nb2/3O3-PbTiO3. The polar structure in these materials in their bulk cubic state can be represented as overlapping anisotropic volumes, each encompassing unit cells with projections of their polarization vectors onto the volume's longest axis pointing in the same direction. The overlap results in swirling topological textures of polarization containing vortices, such as merons, and displaying smooth changes in the polarization directions. The locations of these vortices are linked to the electric charge gradient caused by compositional heterogeneities, deemed to create depolarizing fields.