Recent reports have shown that thulium iron garnet (TmIG) based bilayers are promising material platforms for realizing small, room-temperature skyrmions. For potential applications, it is imperative to accurately evaluate electrical readout signals of skyrmions. In this context, the topological Hall effect has been considered as a characteristic signature of skyrmion formation. Unlike previous studies that have modeled the anomalous Hall effect in ultrathin TmIG/Pt bilayers, we isolate its contribution to the electrical readout signal by directly measuring the magnetic hysteresis loops using a sensitive Sagnac magneto-optical Kerr effect technique. Our combined optical and electrical measurements reveal that the spin Hall topological Hall resistivity is considerably larger than previously estimated values. Our finding further indicates that skyrmions can exist at room-temperature and near-zero applied magnetic fields.This research was primarily supported by the National
Science Foundation through the Center for Dynamics and
Control of Materials: an NSF MRSEC under Coopera-
tive Agreement No. DMR-1720595, and the Center for
Emergent Materials, an NSF MRSEC under Grant No.
DMR-2011876. Additional support was provided by the
Welch Foundation F-1662. Facilities provided by MR-
SEC DMR-1720595 and by NSF MRI DMR-2019130 are
gratefully acknowledged. Partial funding for L. J. Chang
while visiting UT-Austin was provided by a Portugal-UT
collaboration grant. The collaboration between S,F. Lee
and X. Li is facilitated by the AFOSR grant FA2386-21-
1-4067.Center for Dynamics and Control of Material
