Antisite Defects Stabilized by Antiphase Boundaries in YFeO3 Thin Films

YFeO3 thin films are a recent addition to the family of multiferroic orthoferrites where Y-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, the structure and chemistry of antiphase boundaries in Y-rich multiferroic YFeO3 thin films are reported using aberration corrected scanning transmission electron microscopy combined with atomic resolution energy dispersive X-ray spectroscopy. It is found that Fe-Y antisites, which are not stable in the Y-rich film bulk, periodically arrange along antiphase boundaries due to changes in the local structural environment. Using density functional theory, it is shown that the antiphase boundaries are polar and bi-stable, where the presence of Fe-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.

Automated summary

YFeO3 thin films exhibit changes in antiphase boundaries under the influence of Y-Fe antisite defects and strain, displaying polar and bistable characteristics. Density functional theory demonstrates that the presence of Fe-Y antisites significantly decreases the switching barrier.