Confined Magnetization at the Sublattice-Matched Ruthenium Oxide Heterointerface.

Creating a heterostructure by combining two magnetically and structurally distinct ruthenium oxides is a crucial approach for investigating their emergent magnetic states and interactions. Previously, research has predominantly concentrated on the intrinsic properties of the ferromagnet SrRuO and recently discovered altermagnet RuO solely. Here, the study engineers an ultrasharp sublattice-matched heterointerface using pseudo-cubic SrRuO and rutile RuO, conducting an in-depth analysis of their spin interactions. Structurally, to accommodate the lattice symmetry mismatch, the inverted RuO layer undergoes an in-plane rotation of 18 degrees during epitaxial growth on SrRuO layer, resulting in an interesting and rotational interface with perfect crystallinity and negligible chemical intermixing. Performance-wise, the interfacial layer of 6 nm in RuO adjacent to SrRuO exhibits a nonzero magnetic moment, contributing to an enhanced anomalous Hall effect (AHE) at low temperatures. Furthermore, the observations indicate that in contrast to SrRuO single layers, the AHE of [(RuO)/(SrRuO)] heterostructures show nonlinear behavior and reaches its maximum when the SrRuO thickness reaches tens of nm. These results suggest that the interfacial magnetic interaction surpasses that of all-perovskite oxides (≈5-unit cells). This study underscores the significance and potential applications of magnetic interactions based on the crystallographic asymmetric interfaces in the design of spintronic devices.