Ising lines: natural topological defects within chiral ferroelectric domain walls

TL;DR

This paper uses phase-field simulations to reveal a new type of topological defect called Ising lines in rhombohedral ferroelectric BaTiO3, acting as mobile domain boundaries within domain walls.

Contribution

It introduces Ising lines as intrinsic topological defects in ferroelectric domain walls, expanding understanding of domain wall phase transitions.

Findings

Ising lines are about 2 nm thick paraelectric nanorods.

They act as mobile boundaries between Bloch-like domain wall segments.

Ising lines are stable under periodic boundary conditions.

Abstract

Phase-field simulations demonstrate that the polarization order-parameter field in the Ginzburg-Landau-Devonshire model of rhombohedral ferroelectric BaTiO3 allows for an interesting linear defect, stable under simple periodic boundary conditions. This linear defect, termed here as Ising line, can be described as about 2 nm thick intrinsic paraelectric nanorod acting as a highly mobile borderline between finite portions of Bloch-like domain walls of the opposite helicity. These Ising lines play the role of domain boundaries associated with the Ising-to-Bloch domain wall phase transition.