Tuning magnetic anisotropy by interfacially engineering the oxygen coordination environment in a transition metal oxide

Strong correlations between electrons, spins and lattices - stemming from strong hybridization between transition metal d and oxygen p orbitals - are responsible for the functional properties of transition metal oxides. Artificial oxide heterostructures with chemically abrupt interfaces provide a platform for engineering bonding geometries that lead to emergent phenomena. Here we demonstrate the control of the oxygen coordination environment of the perovskite, SrRuO₃, by heterostructuring it with Ca_0.5Sr_0.5TiO₃ (0-4 monolayers thick) grown on a GdScO₃ substrate. We found that a Ru-O-Ti bond angle of the SrRuO₃/Ca_0.5Sr_0.5TiO₃ interface can be engineered by layer-by-layer control of the Ca_0.5Sr_0.5TiO₃ layer thickness, and that the engineered Ru-O-Ti bond angle not only stabilizes a Ru-O-Ru bond angle never seen in bulk SrRuO₃, but also tunes the magnetic anisotropy in the entire SrRuO₃ layer. The results demonstrate that interface engineering of the oxygen coordination environment allows one to control additional degrees of freedom in functional oxide heterostructures.