Anisotropic conductivity of uncharged domain walls in BiFeO3

TL;DR

This paper develops a Landau theory-based model explaining the anisotropic conductivity of uncharged domain walls in BiFeO3, highlighting the role of local band bending, electrostriction, and flexoelectric effects.

Contribution

It introduces a comprehensive analytical framework for understanding anisotropic carrier accumulation at uncharged domain walls in BiFeO3, aligning with experimental and first-principles data.

Findings

Carrier accumulation strongly depends on domain wall angle.

Local band bending is influenced by electrostriction and flexoelectric coupling.

The model suggests diverse electronic properties at ferroic walls.

Abstract

Experimental observations suggest that nominally uncharged, as-grown domain walls in ferroelectric thin films can be conductive, yet comprehensive theoretical models to explain this behavior are lacking. Here, Landau theory is used to evolve an analytical treatment of the anisotropic carrier accumulation by nominally uncharged domain walls in multiferroic BiFeO3. Strong angular dependence of the carrier accumulation by 180-degree domain walls originates from local band bending via angle-dependent electrostriction and flexoelectric coupling mechanisms. Theoretical results are in qualitative agreement with experimental data, and provide a Landau-Ginzburg-Devonshire counterpart that is consistent with recent first principles calculations. These studies suggest that a significantly more diverse range of domain wall structures could possess novel electronic properties than previously believed. Similarly, emergent electronic behaviors at ferroic walls are typically underpinned by multiple mechanisms, necessitating first-principle studies of corresponding coupling parameters.