Abrupt Appearance of the Domain Pattern and Fatigue of Thin Ferroelectric Films

We study the domain structure in ferroelectric thin films with a “passive” (nonferroelectric) layer at the interface between the film and electrodes. An abrupt transition from a monodomain to a polydomain state has been found with the increase of the passive layer thickness $d$. The domain width changes very quickly at the transition (exponentially with $d^{-2\mathrm{}}$). The slope of the hysteresis loop is in agreement with experiment, assuming realistic parameters of the layer. The slope scales as $1/d$, involving only the properties of the layer. We believe that specific properties of the domain structure in ferroelectrics with a passive layer can resolve the long-standing “paradox of the coercive field.”