The effect of interfacial octahedral behavior on magnetic properties in ultrathin manganite films*

In \textit{AB}O$_{3}$ perovskites, the rotation and distortions of $B$O$_{6}$ octahedra lead to crystal symmetric variants of the basic perovskite structure. The rotation angles play a role in magnetic exchange with previous work demonstrating a clear relationship between bond angles and ordering temperatures. Recent work has shown that heteroepitaxial oxide films can be stabilized with non-equilibrium crystal structures due to structural coupling of octahedral behavior across the substrate/film interface. However, it is not yet apparent how the crystal symmetry across a heteroepitaxial oxide interface contributes to magnetic properties. Here, we report on the effect of crystal symmetry in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO), a canonical magnetic oxide, grown using molecular beam epitaxy on different symmetric substrates with similar lattice parameters. For this study, we have used x-ray magnetic circular dichroism, transport, and magnetoresistance measurements to explore the magnetic properties of ultrathin LSMO films for a direct comparison of magnetic behavior in isocompositional perovskites with different octahedral behavior.