Photo-enhanced flexoelectricity or flexoelectricity-enhanced photovoltaic effect, named photo-flexoelectric, is an interesting topic and has application potential in photo-electro-mechanical devices. However, this effect is far from being well understood. In this work, we demonstrate the photoflexoelectric effect in perovskite-structured SrTiO3 (STO) single crystal and reveal the coupling mechanism between its photovoltaic and flexoelectric effect. Driven by the flexoelectric field, light-induced electrons can tunnel through the Schottky junction at the Au/STO interface, giving rise to enhanced flexoelectricity, i.e., photoflexoelectric effect. Thermal annealing in vacuum induces oxygen vacancies in STO and results in stronger light absorption and enlarged photoflexoelectric effect.

Flexoelectricity has been proven to be an effective way in tailoring a material's properties. Here, we report the flexoelectricity-induced transport modulation to the two-dimensional electron gas at the (110) LaAlO 3 /SrTiO 3 systems. Under different strain gradients induced by mechanical bending, the interfacial resistance changes according to the flexoelectric field directions. By measuring the electrical transport properties of the interface under variant strain states, we demonstrate that the modulation effect is affected by the oxygen partial pressure during film deposition. The electrical field effect model can thoroughly explain the observations. These findings further clarify the physical picture of flexoelectric effects in oxide heterostructures.