Exploring conductive domain wall phenomena in ferroelectrics with nitrogen-vacancy magnetometry

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.