Origins of transverse voltages generated by applied thermal gradients and applied electric fields in ferrimagnetic-insulator/heavy-metal bilayers

We compare thermal-gradient-driven transverse voltages in ferrimagnetic-insulator/heavy-metal bilayers (Tm₃Fe₅O₁₂ /W and Tm₃Fe₅O₁₂ /Pt) to corresponding electrically-driven transverse resistances at and above room temperature. We find for Tm₃Fe₅O₁₂/W that the thermal and electrical effects can be explained by a common spin-current detection mechanism, the physics underlying spin Hall magnetoresistance (SMR). However, for Tm₃Fe₅O₁₂ /Pt, this is not the case – the ratio of the electrically-driven transverse voltages (planar Hall signal/anomalous Hall signal) is much larger than the ratio of corresponding thermal-gradient signals, a result which is therefore very different from expectations for a SMR-based mechanism alone. We ascribe this difference to a proximity-induced magnetic layer at the Tm₃Fe₅O₁₂/Pt interface.