Swirling topological textures of polarization in bulk relaxor ferroelectrics

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.