Correlated cation lattice symmetry and oxygen octahedral rotation in perovskite oxide heterostructures

Recent studies have highlighted the collective rotations of corner-shared oxygen octahedra in ABO₃ functional perovskite oxides. However, experimental methods that allow direct measurements of oxygen octahedra, especially for the multilayer containing different types of oxygen octahedral rotations in each layer, are still rare. In this report, the correlation between oxygen octahedral rotation and cation-lattice symmetry is discussed by studying the interface-engineered perovskite La_2/3Sr_1/3MnO₃ layers. The out-of-phase octahedral rotations remove the orthogonality between corresponding axes of the cation lattice, leading to the asymmetric diffraction pattern recorded by the reciprocal space mapping. More importantly, in the La_2/3Sr_1/3MnO₃-multilayer heterostructure, the reciprocal space mapping can identify different octahedral rotations for each La_2/3Sr_1/3MnO₃ layer, explaining the appearance of multiple Curie temperatures and coercive fields. Our results reveal the new understanding of the old reciprocal space mapping-based technique, based on the correlation between oxygen octahedral rotation and cation-lattice symmetry. The application of reciprocal space mapping to the La_2/3Sr_1/3MnO₃-multilayers not only showcases the advantage of this technique but also extends our understanding of oxygen octahedral rotation to the more complicated oxide heterostructures.