Octahedral coupling in (111)- and (001)-oriented La0.7Sr0.3MnO3/SrTiO3 heterostructures

Abstract

Rotations and distortions of oxygen octahedra in perovskites play a key role in determining their functional properties. Here, we investigate how octahedral rotations can couple from one material to another in La2/3Sr1/3MnO3/SrTiO3 epitaxial heterostructures by first principles density functional theory calculations, emphasizing the important differences between systems oriented perpendicular to the (111)- and (001)-facets. We find that the coupling length of out-of-phase octahedral rotations is independent of the crystalline facet, pointing toward a steric effect. However, the detailed octahedral structure across the interface is significantly different between the (111)- and (001)-orientations. For (001)-oriented interfaces, there is a clear difference whether the rotation axis in SrTiO3 is parallel or perpendicular to the interface plane, while for the (111)-interface, the different rotations' axes in SrTiO3 are symmetry equivalent. Finally, we show that octahedral coupling across the interface can be used to control the spatial distribution of the spin density.