Geometric Control of Domain Structure Stability in Ferroelectric Nanotubes

The field of nanoscale ferroelectrics has utilized geometric confinement in thin films, nanodots, nanoislands, and strained superlattices to stabilize flux closures, vortices, skyrmions, and other topologically non-trivial polar states. Ferroelectric nanotubes provide a unique geometry with a large surface-to-volume ratio and vertical to lateral aspect ratio, and from these unique geometric properties, new polarization domain structures can be stabilized with unique flux-closure topologies. Using phase-field modeling, we simulated the equilibrium polarization domain structure in PbZr0.52Ti0.48O3 nanotubes under different height and wall thickness conditions, and three unique domain structures were found. Each domain structure comprises an array of periodic flux-closures and anti-flux-closures pairs formed to minimize elastic and electrostatic energy. These domain structures differ by the frequency of the flux-closure/anti-flux-closure pairs along the perimeter and height. We demonstrate that the thermodynamic stability of these domain structures can be tuned by changing the nanotube geometry with wall thickness and height.