Perovskite Oxide Interfaces Tailored by Cation Ordering Periodicities: Experimentally Resolved Atomic Structure and Predicted Magnetic Coupling.

Magnetically coupled interfaces formed from perovskite oxides with different B-site ordering periodicities have not been studied extensively due to challenges in synthesis and a lack of adequate parent phases. Here, we use aberration-corrected analytical scanning transmission electron microscopy to identify the atomic structure and chemistry of a perovskite oxide interface that exhibits different B-site ordering periodicity on the atomic scale. The interface is formed from the 1:1 B-site-ordered double-perovskite Sr2Fe1+xRe1-xO6 and the 1:2 B-site-ordered triple-perovskite Sr3Fe2ReO9. First-principles calculations on the superlattice model with the same modulation of B-site ordering periodicity observed experimentally show that magnetic coupling between Fe and Re atoms at the interface results in characteristics of ferromagnetism, in contrast to the antiferromagnetic nature of the parent phases. The results suggest that tailoring of B-site ordering periodicity for tuning interfacial magnetism at perovskite oxide interfaces can be potentially applied in epitaxial growth of superlattice thin films with magnetically engineered interfaces.