Mesoscopic mechanism of the domain wall interaction with elastic defects in ferroelectrics

TL;DR

This paper investigates how elastic defects influence the motion of ferroelectric domain walls, revealing that defects cause velocity oscillations and set a lower threshold field for wall movement, with implications for ferroelectric material behavior.

Contribution

It provides a mesoscopic analytical model describing the interaction between elastic defects and domain walls, including the derivation of threshold fields and velocity behaviors.

Findings

Defects cause ripples, steps, and oscillations in domain wall velocity.

Threshold field for wall motion is smaller than the coercive field.

Threshold field depends linearly on defect concentration and non-monotonically on defect spacing.

Abstract

The role of elastic defects on the kinetics of 180-degree uncharged ferroelectric domain wall motion is explored using continuum time-dependent LGD equation with elastic dipole coupling. In one dimensional case, ripples, steps and oscillations of the domain wall velocity appear due to the wall-defect interactions. While the defects do not affect the limiting-wall velocity vs. field dependence, they result in the minimal threshold field required to activate the wall motions. The analytical expressions for the threshold field are derived and the latter is shown to be much smaller than the thermodynamic coercive field. The threshold field is linearly proportional to the concentration of defects and non-monotonically depends on the average distance between them. The obtained results provide the insight into the mesoscopic mechanism of the domain wall pinning by elastic defects in ferroelectrics.