Non-Ising Character of a Ferroelectric Wall Arises from a Flexoelectric Effect

TL;DR

This paper reveals that a ferroelectric domain wall in BaTiO3 is not purely Ising-type but contains charged Bloch and Neel components due to flexoelectric effects caused by stress inhomogeneity.

Contribution

It demonstrates that flexoelectric effects induce charged polarization components in ferroelectric domain walls, challenging the traditional Ising-type assumption.

Findings

Domain wall contains charged Bloch and Neel components.

Flexoelectric effect from stress inhomogeneity causes these components.

Bound charge density at the wall can reach 10^6 to 10^7 Cm^-3.

Abstract

Using the classic ferroelectric BaTiO$_3$ as an example, we show that the 180 degree ferroelectric domain wall, long considered to be of Ising-type and charge neural, contains both Bloch and Neel type polarization components, and is thus charged. The bound charge density at the wall may reach as high as 10$^6$~10$^7$ Cm$^{-3}$. It is demonstrated that the flexoelectric effect arising from stress inhomogeneity is responsible for the additional Bloch and Neel polarization components. The magnitudes of these additional components are determined by the competing depolarization and flexoelectric fields.