Photoinduced Linear Motion of Ferroelectric Domain Walls for Neuromorphic Pattern Recognition

Linear switching of ferroelectric polarization is essential for achieving high precision, sensitivity, and efficiency in ferroelectric devices. However, electric fields inevitably introduce significant nonlinearity into the switching process. Light offers a contactless and low-power route to switch polarization, which has drawn growing research interest. Despite various proposed mechanisms for photoinduced polarization switching, the interpretations remain controversial. Here, we demonstrate that, in ferroelectric BaTiO3 films, light induces linear domain wall motion and a corresponding linear change in the polarization area. These linear and continuously tunable multi-states enable a neuromorphic device with markedly improved pattern recognition accuracy. By combining ferroelectric hysteresis loops, surface potential measurements, and band structure analysis, we elucidate the underlying mechanism: photogenerated charges are separated by the local built-in field arising from surface band bending, which enhances the overall imprint field and thereby promotes the switching of ferroelectric polarization.