Zero-field topological Hall effect in BiSb/MnGa bi-layers as a signature of ground-state skyrmions at room temperature

We observe the signature of zero-field ground-state skyrmions in BiSb topological insulator / MnGa bi-layers by using the topological Hall effect (THE). We observe a large critical interfacial Dzyaloshinskii-Moriya-Interaction energy (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 absence of an external magnetic field, which gives the strong evidence for the existence of thermodynamically stable skyrmions in MnGa/BiSb bi-layers. Our results will give insight into the role of interfacial DMI tailored by suitable material choice and growth technique for generation of stable skyrmions at room temperature.