Intrinsic threshold electric field for domain wall motion in ferroelectrics based on discretized phase-field model

TL;DR

This paper uses discretized phase-field models to investigate the intrinsic threshold electric field needed for domain wall motion in ferroelectrics, revealing size-dependent effects and aligning with experimental and first-principles findings.

Contribution

It introduces a discretized phase-field approach to accurately determine the intrinsic threshold electric field for domain walls, accounting for atomic-scale effects not captured by continuum models.

Findings

Threshold electric field increases as domain wall width decreases.

Significant threshold fields occur when domain walls are thinner than two unit cells.

Results align qualitatively with first-principles and cryogenic experiments.

Abstract

With the development of ferroelectric memories, it is becoming increasingly important to understand the ferroelectric switching behaviors at small applied electric fields. In this \rv{paper}, we use discretized phase-field models to systematically investigate the intrinsic threshold electric field (TEF) to drive flat 180$^\circ$ and 90$^\circ$ domain walls (DWs), which can not be captured by continuum models. The results show that this TEF increases as the ratio of DW width to unit cell size decreases, and it becomes significant if the DW width is thinner than two unit cells. The results are qualitatively consistent with existing first-principles studies and cryogenic experiments. In addition, this work proposes a conceptual model to explain the activation electric field (AEF) observed in experiments at room temperature. This work improves the understanding of DW motion kinetics at small applied fields, and shows that the mesh size and orientation are both important for the phase-field modeling of the above process.