Antisite defects stabilized by antiphase boundaries in YFeO$_3$ thin films

TL;DR

This study investigates how antiphase boundaries in YFeO$_3$ thin films stabilize Fe extsubscript{Y} antisite defects, revealing their structure, chemistry, and impact on the material's multiferroic properties through advanced microscopy and theoretical modeling.

Contribution

It provides detailed atomic-scale insights into the structure and stability of antisite defects at antiphase boundaries in YFeO$_3$ thin films, combining experimental and computational methods.

Findings

Fe extsubscript{Y} antisites stabilize at antiphase boundaries due to local environment changes.

Antiphase boundaries are polar and bi-stable, affecting switching behavior.

Fe extsubscript{Y} antisites lower the energy barrier for polarization switching.

Abstract

YFeO$_3$ thin films are a recent addition to the family of multiferroic orthoferrites where Y\textsubscript{Fe} antisite defects and strain have been shown to introduce polar displacements while retaining magnetic properties. Complete control of the multiferroic properties, however, necessitates knowledge of the defects present and their potential role in modifying behavior. Here, we report the structure and chemistry of antiphase boundaries in multiferroic YFeO$_3$ thin films using aberration corrected scanning transmission electron microscopy combined with atomic resolution energy dispersive X-ray spectroscopy. We find that Fe\textsubscript{Y} antisites, which are not stable in the film bulk, periodically arrange along antiphase boundaries due to changes in the local environment. Using density functional theory, we show that the antiphase boundaries are polar and bi-stable, where the presence of Fe\textsubscript{Y} antisites significantly decreases the switching barrier. These results highlight how planar defects, such as antiphase boundaries, can stabilize point defects that would otherwise not be expected to form within the structure.