Conductive tail-to-tail domain walls in epitaxial BiFeO₃ films

The complex conductive behavior of ferroelectric domain walls is attracting more and more attention for their potential application as an independent nanoelectronic component. For the (001) epitaxial BiFeO₃ films, we find that the domain wall conductivity varies among 71° domain walls, with tail-to-tail (T-T) domain walls more conductive than head-to-head (H-H) and head-to-tail (H-T) ones. Furthermore, it is observed that most of the conductive areas are composed of two parallel lines around the T-T domain walls. These experimental results can be well simulated by our theoretical model based on the polarization configuration and a tunneling mechanism. Our work will help to understand the mechanism of domain wall conductance in ferroelectric materials and further promote the usage of domain walls in advanced nano-devices.