Oxygen-vacancy Mediated Deterministic Domain Distribution at the Onset of Ferroelectricity

TL;DR

This study reveals that oxygen vacancies act as fixed pinning sites influencing the deterministic patterning of ferroelectric domains at the transition temperature, challenging the idea of spontaneous domain formation.

Contribution

It demonstrates that oxygen vacancies govern domain distribution at the onset of ferroelectricity, providing insight into domain pattern reproducibility and memory effects.

Findings

Oxygen vacancies remain immobile above Curie temperature.

Domain patterns are reproducible due to fixed oxygen vacancies.

Memory effects suggest non-spontaneous domain distribution.

Abstract

Ferroelectric domains are mesoscale structures that mediate between synchronized atomic-scale ion displacements and switchable macroscopic polarization. Here, we evaluated the randomness of the domain distribution at the onset of ferroelectricity. First-principle calculations combined with atomic-scale imaging demonstrate that oxygen vacancies that serve as pinning sites for the ferroic domain walls remain immobile above the Curie temperature. Thus, upon cooling to a ferroelectric state, these oxygen vacancies dictate reproducible domain-wall patterning. Domain-scale imaging with variable-temperature piezoresponse force microscopy confirmed the memory effect, questioning the spontaneity of domain distribution under thermotropic transitions.