Stabilization of charged domains in ferroelectric BiFeO3 nanoneedles.

Stabilizing ferroelectric domain configurations is critical to driving the exploration of the fundamental physics and governing principles of domain formation in ferroelectrics. Charged domain walls have attracted interest in nanoelectronics due to their high conductivity but are usually not utilized due to their conventional instability. In this study, we investigate charged domains impacted by reduced dimensionality and surface boundary conditions in BiFeO3 nanoneedles. The BiFeO3 nanoneedle's domain structure was examined in three dimensions using a low-order tilt projection series collected by scanning transmission electron microscopy. We find that surfaces of varying surface curvature can facilitate the formation of charge-compensating surface terminations and can play a role in the stabilization of charged domains in BiFeO3. Additionally, phase-field simulations support the formation of charged domains in the bulk of BiFeO3 nanoneedles by charge domains forming to reduce the total energy at the needle interior through domain wall reconstruction. Our results pave a novel pathway to stabilize inherently unstable charged domains in ferroelectric oxides and provide insights into geometric boundary condition engineering of thin films and nanostructures.