Observation of Atomic-Scale Polar Vortex-Antivortex Pairs in Antiferroelectric PbZrO₃ Thin Films

Topological polar structures, in analogy to spin vortices and skyrmions, have received tremendous attention for their fascinating prospects in future device applications. However, in the widely studied ferroelectric-based superlattices, the epitaxial heterointerfaces, yielding desired strain, depolarization, and gradient energies, greatly confine the mobility of the topological solitons. Here, we report observation of polar vortex-antivortex pairs near junctions of antiphase boundaries in antiferroelectric PbZrO₃ thin films by using atomic-resolution scanning transmission electron microscopy. Our temporal-resolved lattice analysis reveals that the local strain gradient caused by an incommensurate modulation constructs the smallest topological units reported to date. Our phase-field simulations unveil that the Pb-O vacancy-induced random electric fields account for their three-dimensional formation, and the stimulus of electron-beam irradiation can drive their dynamic migration. The findings offer a new approach to comprehend fundamental physics about antiferroelectricity and the design of functional devices based on topological structures in antiferroelectric thin films.