Artificial Domain Patterning in Ultrathin Ferroelectric Films via Modifying the Surface Electrostatic Boundary...

Nanoscale spatially controlled modulation of the properties of ferroelectrics via artificial domain pattering is crucial to their emerging optoelectronics applications. New patterning strategies to achieve high precision and efficiency and to link the resultant domain structures with device functionalities are being sought. Here, we present an epitaxial heterostructure of SrRuO₃/PbTiO₃/SrRuO₃, wherein the domain configuration is delicately determined by the charge screening conditions in the SrRuO₃ layer and the substrate strains. Chemical etching of the top SrRuO₃ layer leads to a transition from in-plane a domains to out-of-plane c domains, accompanied by a giant (>10⁵) modification in the second harmonic generation response. The modulation effect, coupled with the plasmonic resonance effect from SrRuO₃, enables a highly flexible design of nonlinear optical devices, as demonstrated by a simulated split-ring resonator metasurface. This domain patterning strategy may be extended to more thin-film ferroelectric systems with domain stabilities amenable to electrostatic boundary conditions.