Control of Domain States in Rhombohedral Lead Zirconate Titanate Films via Misfit Strains and Surface Charges

Abstract

AbstractUsing the Landau–Ginzburg–Devonshire approach and numerical modeling, an influence of the misfit strain and surface screening charges as well as the role of the flexoelectric effect have been studied in the case of a rhombohedral lead zirconate titanate ferroelectric/ferroelastic thin film with an anisotropic misfit caused by a substrate. The magnitude and sign of the misfit strain influence the domain structure, providing misfit‐dependent phases with different favorable polarization components. Whilst strong enough compressive misfit strains favor a phase with orthorhombic‐like polarization directions, strong tensile misfits only yield in‐plane polarization components. The strength of surface screening conditions the existence of closure domain structures and, by increasing, supports the single‐domain state. The flexoelectric effect exhibits a weak influence on the phase diagram of multi‐domain states when compared with the phase diagram of single‐domain states. Its effect, however, becomes significant in the case of skyrmion topological states spontaneously formed near the film surface when compressive misfit strains are applied. Cooperative influence of the misfit strain, surface screening charges, and temperature can set a thin rhombohedral ferroelectric film into a number of different polar and structural states, whereby the role of the flexoelectric effect is pronounced for topologically nontrivial structures.