Topological Hall Effect in SrTiO₃/SrIrO₃/SrRuO₃ Superlattices

Ferromagnet(FM)/heavy-metal(HM) bilayers films have been found to able to host topological magnetic structures like skyrmions stabilized by exchange and interfacial Dzyaloshinskii-Moriya interactions. Electrical measurement by the topological Hall effect (THE) has been a primary method of detection of these features. Perovskites multilayers are an excellent platform for investigating these systems due to the wide range of electrical and magnetic properties and very low lattice mismatch allowing for the growth of high-quality films. Here we investigated the topological hall effect in STO(001)/SrRuO₃/SrIrO₃/SrTiO₃ superlattices where SrTiO₃ acts as a spacer layer that seperates the FM/HM layers SrRuO₃/SrIrO₃. As the spacer thickness was increased, the magnitude of the topological Hall resistivity decreased suggesting interlayer coupling. Superlattices with thinner spacer layers show a transition between two topological hall peaks corresponding to before and after the magnetization has switched and an intermediate temperature where both signal are observed. This behavior appears to be unique to the superlattices and is not seen in bilayer structures.