Artificial Grain Boundaries Created by Freestanding Membrane Transfer Reveal Angle-Dependent Ferroelectric Switching...

Grain boundaries (GBs) strongly influence polycrystalline ferroelectrics, but their discrete effects are difficult to isolate because of nanoscale heterogeneity. Here, we use freestanding membrane transfer to fabricate artificial ${\text{BaTiO}}_3$ GBs with controlled, experimentally accessible in-plane misorientation angles ( $\varphi$ ). Macroscopic electrical measurements show higher coercive voltage and leakage current at the GB region than in the coherent grain region. Piezoresponse force microscopy directly reveals domain-wall pinning at the boundary, which impedes lateral domain propagation and increases the effective switching barrier. Conductive atomic force microscopy further identifies the GB as a localized high-conductance pathway, with leakage increasing strongly with, $\varphi$ in agreement with a Read-Shockley-inspired model. Temperature-dependent steady-state DC measurements yield an activation energy of approximately 0.032 eV at the GB, an order of magnitude lower than in the grain interior. Comparison of Schottky and Poole-Frenkel analyses indicates that transport is more consistent with defect-assisted, Schottky-like thermally activated emission than with bulk Poole-Frenkel conduction. These results establish a tunable artificial-GB platform that directly correlates misorientation angle with domain-wall pinning, coercive voltage, and localized leakage, providing a pathway for grain-boundary engineering in ferroelectric thin films.