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

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 SrRuO 3 /PbTiO 3 /SrRuO 3 , wherein the domain configuration is delicately determined by the charge screening conditions in the SrRuO 3 layer and the substrate strains. Chemical etching of the top SrRuO 3 layer leads to a transition from in-plane a domains to out-of-plane c domains, accompanied by a giant (>10 5 ) modification in the second harmonic generation response. The modulation effect, coupled with the plasmonic resonance effect from SrRuO 3 , 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.