Anisotropic conductivity of uncharged domain walls in BiFeO₃

Abstract

Experimental observations suggest that nominally uncharged, as-grown domain walls in ferroelectrics can be conductive, yet comprehensive theoretical models to explain this behavior are lacking. Here, Landau-Ginzburg-Devonshire 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° 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 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-principles studies of corresponding coupling parameters.