Nanoscale stress-induced conducting states in functional oxides

Abstract

The potential for active nano-electronic devices based on the creation and manipulation of pseudo-2D electrically conducting interfaces, such as domain walls and phase boundaries, in an array of material systems is now well established. Whilst the existence of conducting interfaces within otherwise insulating mediums is surprising, exciting new avenues for fundamental research have developed, focussing on harnessing the potential for these conducting channels to be active components within nanoscale devices. With the nucleation and repositioning of conducting interfaces having been to date, reliant primarily on the use of electric-field poling regimes; a series of recent studies utilising mechanical stress as a means of controlling nanoscale phase transitions and functionality, offers an alternate approach for direct injection and control of conducting interfaces. Moreover, with the advent of scanning probe microscopy (SPM), large magnitudes of stress can be applied in a highly localised manner via nanoscale probe tips, making this process ideally suited for materials possessing confined geometries. This thesis seeks to address the role that highly localised stress plays in inducing conducting states on the nanoscale within two unique material systems; ferroelectric mixed-phase Bismuth Ferrite, and the metalinsulator transition oxide, Vanadium Dioxide.

Date of Award	Jul 2018
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Amit Kumar (Supervisor) & Marty Gregg (Supervisor)