Ultrafast Domain Manipulation in Ferroelectrics via Bulk Photovoltaic Effect: A Phase-Field Study

Optical control of ferroelectricity is crucial for advancing optoferroic devices. While recent research has shown that optical methods can indirectly couple to ferroelectric polarization through thermal depolarization, photostriction, and magnetoelectric effects, the impact of light-induced space charges on domain reconfiguration remains underexplored. In this work, we study the bulk photovoltaic (BPV) effect in ferroelectric oxides, where photoexcited carrier separation occurs under above-bandgap illumination due to their non-centrosymmetric nature. We developed a phase-field model incorporating the BPV effect to achieve a microscopic understanding of the interplay between ferroelectric domains and BPV currents at ultrafast timescales. Our results reveal that variations in BPV currents between adjacent domains generate opposite charges at domain walls, enhancing the internal electric field up to 1000 kV/cm. This intense field can rotate polarization and facilitate domain wall movement on sub-picosecond scales, enabling non-volatile domain evolution assisted by anisotropic biaxial strain. This study advances the fundamental understanding of BPV effects in ferroelectrics and demonstrates a pathway for ultrafast domain manipulation, with potential applications in opto-ferroelectric memory devices.