Theoretical investigation of magnetic anisotropy at the La0.5Sr0.5MnO3/LaCoO2.5 interface

Based on density functional theory calculations, we show how symmetry mismatch at interface induces perpendicular magnetic anisotropy (PMA) for the perovskite/brownmillerite-typed $\mathrm{L}{\mathrm{a}}_{1/2}\mathrm{S}{\mathrm{r}}_{1/2}\mathrm{Mn}{\mathrm{O}}_{3}/\mathrm{LaCo}{\mathrm{O}}_{2.5}$ superlattices in different strain states. We found strong interfacial reconstructions, which result in considerable orbital hybridization due to distortion/tilting of the $\mathrm{Mn}{\mathrm{O}}_{6}$ octahedron and $\mathrm{Co}{\mathrm{O}}_{4}$ tetrahedron. We identified the orbital pairs that strongly affect magnetic anisotropy, showing that tuning the degree of orbital hybridization by lattice strain is an effective approach to tune magnetic anisotropy. Remarkably, not only octahedron-coordinated Mn ions but also tetrahedron-coordinated Co ions contribute to PMA. This work presents a guidance for tuning spin orientation by interface engineering.