Optical Control of Ferroelectric Domains: Nanoscale Insight into Macroscopic Observations

Abstract Domain wall nanoelectronics constitutes a potential paradigm shift for next‐generation energy conversion and von‐Neumann devices. In this context, attempts have been made to achieve energy‐efficient control over ferromagnetic, ferroelectric, and ferroelastic domain walls through electric and magnetic fields or applied stress. However, optical control of ferroic domains offers an additional degree of freedom and significant advantages of reduced hysteresis and Joule heating losses, creating novel opportunities in the regime of nanoelectronics and photonics. Herein, the reversible optical control of ferroelectric domains and domain walls in a novel band‐gap‐engineered lead‐free ferroelectric ceramic ((K_0.5Na_0.5)NbO₃–2 mol% Ba(Ni_0.5Nb_0.5)O_3−δ ) is demonstrated. The optical poling behaves similar to electrical poling and is governed by the bulk ferroelectric photovoltaic effect. The light‐generated charge carriers are transported toward domain walls or electrodes due to a nonzero field in the samples. This causes a change in internal electric field influencing the nanoscale state of polarization, which could also be interesting for other ferroelectrics if the voltage generated by light is in the range of the switching voltages. This work establishes a relationship between light‐induced macroscopic observations and nanoscale changes in the ferroelectric response, providing fundamental insight and facilitating research into ferroelectric photovoltaics and optoelectronics.