Spontaneous Vortex Nanodomain Arrays at Ferroelectric Heterointerfaces

TLDR

The importance of magnetization closure has long been appreciated in multidomain ferromagnetic systems, and imaging this analogous effect with atomic resolution at ferroelectric heterointerfaces enables observation of device‑relevant interface issues. The study aims to extend this technique to visualize domain dynamics. The authors image the polarization of BiFeO₃ under varying electrical boundary conditions at heterointerfaces with atomic resolution using a spherical aberration‑corrected transmission electron microscope. The study observes triangular‑shaped vortex nanodomain arrays at ferroelectric heterointerfaces, with phase‑field simulations showing they provide polarization closure; these arrays exhibit mixed Ising–Néel domain walls, enhanced in‑plane polarization, and altered switching behavior, highlighting heterointerfaces as critical to device performance.

Abstract

The polarization of the ferroelectric BiFeO3 sub-jected to different electrical boundary conditions by heterointerfaces is imaged with atomic resolution using a spherical aberration-corrected transmission electron microscope. Unusual triangular-shaped nanodomains are seen, and their role in providing polarization closure is understood through phase-field simulations. Heterointerfaces are key to the performance of ferroelectric devices, and this first observation of spontaneous vortex nanodomain arrays at ferroelectric heterointerfaces reveals properties unlike the surrounding film including mixed Ising−Néel domain walls, which will affect switching behavior, and a drastic increase of in-plane polarization. The importance of magnetization closure has long been appreciated in multidomain ferromagnetic systems; imaging this analogous effect with atomic resolution at ferroelectric heterointerfaces provides the ability to see device-relevant interface issues. Extension of this technique to visualize domain dynamics is envisioned.