Strain engineering and atomic defect interaction in BiFeO ₃ via Fe implantation for enhanced polarization response

Abstract The accelerating demands of Artificial Intelligence (AI) Dynamic Random‐Access Memory and the Internet of Things (IoT) applications call for next‐generation non‐volatile memory devices with high speed and nanoscale integration. BiFeO 3 (BFO) ferroelectric thin films are promising candidates for beyond‐von Neumann architectures but suffer from intrinsic defects, particularly oxygen vacancies, which degrade polarization stability and increase the leakage current. Herein, we report an atomic‐scale lattice engineering approach based on precisely controlled Fe 3+ ‐ion implantation to modulate the [FeO 6 ] octahedral framework in BFO. Atomic‐resolution scanning transmission electron microscopy imaging and polarization vector mapping reveal that optimized implantation induces controlled in‐plane compressive strain, which systematically modifies octahedral tilt patterns. This strain‐mediated distortion simultaneously suppresses oxygen vacancies, enhances Fe 3+ –O 2− orbital hybridization, and facilitates the formation of ordered defect–dipole arrays. Consequently, the implanted films demonstrate a 50% enhancement in remanent polarization along with a 10‐fold reduction in leakage current. By establishing a quantitative relationship between implantation dose, octahedral distortion, and ferroelectric response, this work provides a predictive model for strain–defect–dipole engineering in perovskite oxides, offering a generalizable strategy for optimizing performance in oxide nanoelectronics.