Observation of room temperature topological Hall effect in thin film magnetic insulator/heavy metal bilayers

Magnetic skyrmions are spin textures that are promising for future spintronics-based memory storage owing to their nanoscale structure, topological robustness and the ability to be manipulated with current densities as low as ~10² A/cm². Therefore, from an application standpoint, it is vital to engineer materials that can stabilize skyrmions at room temperature. Magnetic insulators provide the ideal platform for skyrmion stabilization due to their absence of Joule heating and low Gilbert damping. In this talk, we demonstrate the observation of the topological Hall effect (THE) – a signature of magnetic skyrmions – in Li_0.5Al_1.0Fe_1.5O₄ (LAFO)/Pt bilayers. LAFO is a ferromagnetic insulating spinel that we have previously demonstrated to have ultra-low damping and high spin Hall angles (~0.1-0.6) when interfaced with Pt. By tuning LAFO’s magnetic anisotropy with thickness, we show that for < 4 nm films, we can observe THE even at room temperature and stabilize skyrmions for a large portion of the temperature-field phase space. These results highlight the potential for LAFO to act as a platform for current-driven skyrmion manipulation at room temperature, and combined with its low damping and high spin Hall angles, make LAFO a very promising material for future spin current based-applications.