Zero-field topological Hall effect as evidence of ground-state skyrmions at room temperature in BiSb/MnGa bilayers

We observe the signature of zero-field ground-state skyrmions in BiSb topological insulator/MnGa bilayers by using the topological Hall effect (THE). We observe a large critical interfacial Dzyaloshinskii-Moriya-Interaction (DMI) energy (DCS = 5.0 pJ/m) at the BiSb/MnGa interface that can be tailored by controlling the annealing temperature of the MnGa template. The THE was observed at room temperature even under the absence of an external magnetic field, which gives strong evidence of the existence of thermodynamically stable skyrmions in the MnGa/BiSb bilayers. Our results give insight to the role of interfacial DMI tailored by suitable material choice and growth technique for the generation of stable skyrmions at room temperature.