Imaging ferroelectric hysteresis and domain wall pinning

TL;DR

This paper uses advanced scanning probe microscopy to visualize ferroelectric domain wall pinning and polarization reversal mechanisms, revealing how grain boundaries and surface morphology influence domain dynamics.

Contribution

It provides direct imaging evidence of domain wall pinning at grain boundaries and within grains, elucidating the processes of polarization reversal in ferroelectric thin films.

Findings

Pinning occurs strongly at grain boundaries

Weak pinning occurs within grains

Domain reversal involves nucleation and domain wall spreading

Abstract

Simultaneous imaging of the piezoresponse phase, amplitude and bare surface topography of displacive ferroelectric thin films by scanning probe microscopy directly shows the nature of domain wall pinning and its relation to morphological disorder. Strong and stable pinning of walls occurs at grain boundaries while weak and unstable pinning occurs within the grains. The results show that polarization reversal consists of both nucleation of domains and spreading of domain walls, the latter being the dominant process in multi-grain regions. A characteristic single-grain switching in faceted grains is observed as the motion of a single domain wall parallel to one of the facets.