Role of depolarization in the polarization reversal in ferroelectrics

Abstract

Atomistic first-principles-based simulations are used to investigate polarization reversal in ferroelectrics in both the intrinsic and extrinsic regimes in order to determine the origin of nearly an order of magnitude difference in the coercive field predicted theoretically and observed in experiments. We find that the residual depolarizing field that is routinely ignored from considerations is responsible for the drastic reduction of the coercive field. The depolarizing field stabilizes a polydomain phase which allows for counterintuitive cooperation with the applied field to achieve polarization reversal in an energy-efficient way. Contrary to the common belief that low coercive field necessitates polarization reversal via domains formation and propagation, we predict that the same fields could be achieved if the residual depolarizing field is taken into account. An efficient way to incorporate such depolarizing field in any type of atomistic simulations is proposed, which is expected to resolve the longstanding issue of overestimation of fields in simulations of ferroelectrics.