Topological Hall effect at above room temperature in heterostructures composed of a magnetic insulator and a heavy metal

Magnetic skyrmions are topologically robust nanoscale spin textures that can be manipulated with low current densities and are thus potential information carriers in future spintronic devices. Skyrmions have so far been mainly observed in metallic films, which suffer from ohmic losses and therefore high energy dissipation. Magnetic insulators could provide a more energy-efficient skyrmionic platform due to their low damping and absence of Joule heat loss. However, skyrmions have previously been observed in an insulating compound (Cu2OSeO3) only at cryogenic temperatures, where they are stabilized by a bulk Dzyaloshinskii-Moriya interaction. Here, we report the observation of the topological Hall effect-a signature of magnetic skyrmions-at above room temperature in a bilayer heterostructure composed of a magnetic insulator (thulium iron garnet, Tm3Fe5O12) in contact with a metal (Pt). The dependence of the topological Hall effect on the in-plane bias field and the thickness of the magnetic insulator suggest that the magnetic skyrmions are stabilized by the interfacial Dzyaloshinskii-Moriya interaction. By varying the temperature of the system, we can tune its magnetic anisotropy and obtain skyrmions in a large window of external magnetic field and enhanced stability of skyrmions in the easy-plane anisotropy regime.