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oai:figshare.com:article/32805782 2026-10-01T16:13:05Z portal_1172 item_type_8 month_year_10_2026

Exploring conductive domain wall phenomena in ferroelectrics with nitrogen-vacancy magnetometry James Michael Dalzell (24292919) PUREID: 688707404 Nitrogen vacancy NV ferroelectrics magnetomety domain wall Ferroelectric domain walls are moveable, controllable and highly functional nanoscale elements that can exhibit electronic properties not present in the surrounding bulk. Despite considerable progress, a central challenge remains in the ability to quantitatively measure and evaluate the physics governing charge transport along these nanoscale structures. Conventional transport studies rely heavily on conductive atomic force microscopy (cAFM), which suffers from intrinsic limitations: its two-probe configuration couples current injection and detection, while tip wear, coating degradation and environmental effects contribute to poor reproducibility. As a result, reported carrier densities and mobilities often span several orders of magnitude across the literature.<br><br>This thesis investigates nitrogen-vacancy (NV) centre magnetometry as an alternative method for probing current flow along conductive ferroelectric domain walls. By monitoring shifts in the spin-resonance frequencies of NV centres in response to local magnetic fields, quantitative measurements of the current-generated Oersted field can be obtained, enabling non-contact imaging of current density with nanoscale resolution.<br><br>A full current-density reconstruction framework was implemented and validated using a metallic test structure, confirming the validity of the approach and establishing a minimum detectable current density of approximately 1 × 10⁴ A cm⁻². The methodology was then applied to two ferroelectric systems. In erbium manganite, experimental challenges including complex domain topography and weak in-plane currents prevented detection above the DC-ODMR threshold. In thin-film lithium niobate, current-density maps correlated directly with the underlying domain microstructure, revealing that only a small fraction of the domain-wall network carried the majority of the current. This observation necessitated a revision of previously inferred carrier densities, with the active values found to be approximately two orders of magnitude larger than those reported from conventional measurements.<br><br>Overall, this thesis establishes the essential experimental and analytical groundwork for applying NV magnetometry to ferroelectric domain-wall conduction, demonstrating that the technique can reveal transport behaviour inaccessible to conventional methods. 2026-10-01T16:13:05Z Text Thesis 10.17034/32805782.v1 https://figshare.com/articles/thesis/Exploring_conductive_domain_wall_phenomena_in_ferroelectrics_with_nitrogen-vacancy_magnetometry/32805782 All Rights Reserved