Easy collective polarization switching in ferroelectrics

TL;DR

This paper investigates the longstanding puzzle of polarization switching in ferroelectrics, revealing that long-range interactions between nuclei enable barrierless growth of embryonic nuclei, thus explaining the switching mechanism.

Contribution

It introduces a model considering long-range interactions between nuclei, demonstrating how they facilitate polarization switching without overcoming large nucleation barriers.

Findings

Ensembles of small nuclei grow without barriers.

Long-range interactions are key to solving the coercive field paradox.

Classical nucleation barriers remain insurmountable in simplified models.

Abstract

The actual mechanism of polarization switching in ferroelectrics remains a puzzle for many decades, since the usually estimated barrier for nucleation and growth is insurmountable ("paradox of the coercive field"). To analyze the mechanisms of the nucleation we consider the exactly solvable case of a ferroelectric film with a "dead" layer at the interface with electrodes. The classical nucleation is easier in this case but still impossible, since the calculated barrier is huge. We have found that the {\em interaction} between the nuclei is, however, long range, hence one has to study an {\em ensemble} of the nuclei. We show that there are the ensembles of small (embryonic) nuclei that grow {\em without the barrier}. We submit that the interaction between nuclei is the key point for solving the paradox.