Domain patterns and domain wall dynamics in small-scale ferroelectrics
type: CreativeWork
description: This thesis attempts to address two major themes: firstly, the intrinsic dynamics of switching in meso/nanoscale ferroelectrics incorporated into device geometries, and secondly, the development of control over the precise mechanics of switching by altering the ferroelectric morphology therein. In addressing the first theme, thin single-crystal slices of BaTiO^ (or ‘lamellae’), have been incorporated into co-planar electroded test structures. Piezoresponse Force Microscopy (PFM) imaging revealed that switching was carried out by redistribution of highly-ordered packets of 90° ferroelastic domains, or ‘superdomains’, which exhibit a net in-plane polarisation aligned (or anti-aligned) with the switching field. Ferroelectric switching was mediated mainly by the motion of boundaries separating these superdomains whilst the ferroelastic substructure remained largely inactive. In-situ PFM (i.e. imaging during planar switching) revealed that superdomains exhibit the classic nucleation, forwards growth, and sidewards growth modes observed in simple 180° domain switching experiments. Real-time imaging of field-driven superdomain boundary motion showed that the boundary slowed down dramatically after it was set into motion. This bore a striking similarity to the ballistic dynamics of a particle. Hence Newtonian equation of motion fits were attempted to describe the dynamics. However, such an inertial description of the boundary dynamics was found to be unphysical. Instead, interplay between applied and residual depolarising fields in the system was suspected to be at the heart of the apparent ballistic-like dynamics. In studying the long-term relaxation of switched states a large fluxclosing quadrant domain configuration was seen to form, spanning micrometre spatial scales. Its development was rationalised to be driven by residual inplane depolarising fields in the system due to incomplete bound charge compensation at the electrodes. The unusually large size of the quadrant c…
abstract: This thesis attempts to address two major themes: firstly, the intrinsic dynamics of switching in meso/nanoscale ferroelectrics incorporated into device geometries, and secondly, the development of control over the precise mechanics of switching by altering the ferroelectric morphology therein. In addressing the first theme, thin single-crystal slices of BaTiO^ (or ‘lamellae’), have been incorporated into co-planar electroded test structures. Piezoresponse Force Microscopy (PFM) imaging revealed that switching was carried out by redistribution of highly-ordered packets of 90° ferroelastic domains, or ‘superdomains’, which exhibit a net in-plane polarisation aligned (or anti-aligned) with the switching field. Ferroelectric switching was mediated mainly by the motion of boundaries separating these superdomains whilst the ferroelastic substructure remained largely inactive. In-situ PFM (i.e. imaging during planar switching) revealed that superdomains exhibit the classic nucleation, forwards growth, and sidewards growth modes observed in simple 180° domain switching experiments. Real-time imaging of field-driven superdomain boundary motion showed that the boundary slowed down dramatically after it was set into motion. This bore a striking similarity to the ballistic dynamics of a particle. Hence Newtonian equation of motion fits were attempted to describe the dynamics. However, such an inertial description of the boundary dynamics was found to be unphysical. Instead, interplay between applied and residual depolarising fields in the system was suspected to be at the heart of the apparent ballistic-like dynamics. In studying the long-term relaxation of switched states a large fluxclosing quadrant domain configuration was seen to form, spanning micrometre spatial scales. Its development was rationalised to be driven by residual inplane depolarising fields in the system due to incomplete bound charge compensation at the electrodes. The unusually large size of the quadrant c…
author: McQuaid, Raymond Gerard
language: eng
date published: 2012-12
date modified: 2026-07-24T03:55:05Z
provider: Queen's University Belfast
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Queen's University Belfast