Spinodal single-domain → polydomain transition and P-E hysteresis in thin ferroelectric films

This study investigates the spinodal mechanism of domain formation and switching through the loss of stability of a single-domain (SD) state with respect to a polydomain (PD) state in thin ferroelectric films with dead layers. The macroscopic thermodynamic model of a homogenized domain structure (DS) is used to analyze the depolarizing field effect on the transitions between SD and PD states and the shape of the P(E) hysteresis loop. Phase field modeling is used to study the inhomogeneities and film thickness effects on DS and P(E) hysteresis. Such modeling of relatively thick films produces P(E) hysteresis loops of a shape similar to that predicted by the macroscopic model. The results of the analysis demonstrate that the SD -> PD transition can proceed by the spinodal mechanism in thin films, while the nucleation and growth mechanism should operate in thick films. It is shown that columnar and stripe DS can be produced in thin films. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.