Microstructural dynamics induced by nanoscale stress in ferroelectrics

Ferroelectric materials are defined by a spontaneous polarisation that is reversible under an electric field, and represent promising candidates for various applications including data storage and nanoelectronic devices. A crucial aspect of harnessing the functionality of ferroelectrics for such devices involves locally controlling and understanding the microstructural dynamics such as ferroelectric switching behaviour and domain wall motion. Intuitively, electric fields have been extensively used to probe and provide insight into these dynamics. Some studies have also investigated the role of mechanical stress on ferroelectrics, and with the advent of atomic force microscopy (AFM), it is now possible for large stresses to be applied from nanoscale AFM tips in a controlled, highly localised manner that is ideally suited to thin films. In this context, recent studies have shown that nanoscale stress can be used to cause ferroelectric switching in ultra-thin films through the flexoelectric effect. Beyond ultra-thin films however, a number of open questions still remain on the role of nanoscale stress on the numerous ferroelectric materials which possess a strong coupling to stress: for instance, thin films which possess a coexistence of phases due to misfit strain from an underlying substrate and improper ferroelectrics where ferroelectricity occurs as a by-product of ferroelasticity. This gives rise to the possibility of a broad range of different microstructural dynamics which can be induced by nanoscale stress, some of which this thesis aims to explore.

Name dc:type.qualificationname

Doctor of Philosophy

Level dc:type.qualificationlevel

Doctoral Thesis

Grantor dc:publisher.institution

Queen's University Belfast

Year dc:date.issued

2018

Author dc:creator

• Edwards, David

Advisors dc:contributor.advisor

• Gregg, John
• Kumar, Amit

Language dc:language

eng

Identifier

oai:pure.qub.ac.uk/portal:studenttheses/a8859b2a-596b-495f-a36d-458257b2a3bd

OAI identifier oai:identifier

oai:pure.qub.ac.uk/portal:studenttheses/a8859b2a-596b-495f-a36d-458257b2a3bd