The effects of surface morphology on polarization switching in thin ferroelectric films areinvestigated using a real-space, time-dependent Ginzburg–Landau model that incorporateselectrostatic interactions. We consider a two-dimensional uni-axial ferroelectric film with athickness that varies sinusoidally. Polarization switching, starting from a single domain remnantstate, is simulated for several surface modulation amplitudes and wavelengths. We demonstratethat surface heterogeneities produce inhomogeneities in the electric field within the film. Theseinhomogeneities become preferential sites for easy nucleation of reverse domains. This has aprofound effect on the external field necessary to switch the polarization. Increasing the surfaceundulation amplitude significantly reduces the coercive field compared to the ideal flat film,even for very small amplitude modulations in the thickness. Although surface roughnessdecreases the field required to form reverse domains, it also hinders subsequent domain wallmigration. In fact, for very high amplitude and small wavelength surface morphologies,complete switching to a single domain state becomes impossible. This is because the domainwalls become trapped near the peaks in the modulated surface. The technological implicationsof the present results for utilization of surface roughness and for surface morphology design arediscussed.
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