Chemical heterogeneity at conducting ferroelectric domain walls

TL;DR

This study combines transport measurements and atom probe tomography to reveal chemical heterogeneity at ferroelectric domain walls in BiFeO3, explaining diverse conduction mechanisms and their coexistence.

Contribution

It provides the first atomic-scale correlation between chemical composition and electrical properties at ferroelectric domain walls, unveiling chemical variability as a key factor.

Findings

Significant chemical variations along domain walls.

Multiple conduction mechanisms coexist within individual walls.

Chemical heterogeneity influences local electronic properties.

Abstract

Natural interfaces in ferroic oxides have developed into versatile playgrounds for studying electronic correlation effects in 2D systems. The microscopic origin of the emergent local electronic properties is often debated, however, as quantitative atomic-scale characterization remains challenging. A prime example is enhanced conductivity at ferroelectric domain walls, attributed to mechanisms ranging from local band gap reduction to point defect accumulations. Here, we resolve the microscopic mechanisms for domain wall conduction in the ferroelectric model system BiFeO3, by combining transport measurements with atom probe tomography to quantify the local chemical composition and correlate it with the electrical properties. Significant chemical variations along the walls are observed, demonstrating an outstanding chemical flexibility at domain walls, which manifest in spatially varying physical properties. The results give a unifying explanation for the diverse electronic behavior observed and establish the fundamental notion that multiple conduction mechanisms can coexist within individual domain walls.