Antisite defects stabilized by antiphase boundaries in multiferroic YFeO₃ thin films

Controlling the response of multiferroic materials to applied magnetic and electric fields necessitates knowledge of the defects present and their potential role in modifying behavior. In this presentation, we will report on the structure and chemistry of antiphase boundaries in Y-rich multiferroic YFeO₃ thin films using aberration corrected scanning transmission electron microscopy and theory. Combining imaging with atomic resolution energy dispersive X-ray spectroscopy, we find that Fe_Y antisites, which are not stable in the film bulk, periodically arrange along antiphase boundaries due to changes in the local structural environment. The impact that the point and planar defects will also be explored through theory. For example, using density functional theory, we will show that the antiphase boundaries are polar and bi-stable, where the presence of Fe_Y antisites significantly decreases the switching barrier. Finally, we will discuss how these results highlight that planar defects, such as antiphase boundaries, can stabilize point defects that would otherwise not be expected to form within the structure.