Disentangling ferroelectric wall dynamics and identification of pinning mechanisms via deep learning

TL;DR

This paper introduces a deep learning workflow combining segmentation and autoencoders to analyze ferroelectric domain wall dynamics, revealing mechanisms of polarization switching and pinning in polycrystalline materials.

Contribution

It presents a novel combination of deep learning segmentation and non-linear dimensionality reduction to identify and analyze ferroelectric domain wall mechanisms.

Findings

Identifies and classifies ferroelectric and ferroelastic domain walls.

Discovers latent representations of domain wall geometries and dynamics.

Provides insights into pinning mechanisms and their correlation with wall distribution.

Abstract

Field-induced domain wall dynamics in ferroelectric materials underpins multiple applications ranging from actuators to information technology devices and necessitates a quantitative description of the associated mechanisms including giant electromechanical couplings, controlled non-linearities, or low coercive voltages. While the advances in dynamic Piezoresponse Force Microscopy measurements over the last two decades have rendered visualization of polarization dynamics relatively straightforward, the associated insights into the local mechanisms have been elusive. Here we explore the domain dynamics in model polycrystalline materials using a workflow combining deep learning-based segmentation of the domain structures with non-linear dimensionality reduction using multilayer rotationally-invariant autoencoders (rVAE). The former allows unambiguous identification and classification of the ferroelectric and ferroelastic domain walls. The rVAE discover the latent representations of the domain wall geometries and their dynamics, thus providing insight into the intrinsic mechanisms of polarization switching, that can further be compared to simple physical models. The rVAE disentangles the factors affecting the pinning efficiency of ferroelectric walls, offering insights into the correlation of ferroelastic wall distribution and ferroelectric wall pinning.