Emergent topological phase transition dynamics of polar skyrmions*

Polar topological textures—skyrmions, vortices, and merons—have uniquely been observed and robustly stabilized in epitaxial confined ferroelectrics. Therein, interfacial constraints favor the non-uniform rotation of polarization within the polar layers, leading to the formation of emergent topological structures due to the low-dimensionality of these systems. These topologies characterize phases concomitant with exotic functional properties, motivating exploration into ways to extrinsically manipulate these features. Here, using scanning convergent beam electron diffraction, X-ray holography, and phase-field simulations, we demonstrate that polar skyrmions in (PbTiO₃)_n/(SrTiO₃)_n superlattices form a phase characterized by interactions that are extrinsically tunable via temperature and strain, enabling control over phase transitions between distinct ordering configurations and topological states. I will discuss several emerging techniques we have employed to examine the interplay between emergent phenomena—namely topology, ordering, and chirality—and extrinsic parameters, to describe the topological phase diagram and phenomenology of polar oxide superlattices.