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 impera-
tive to accurately evaluate electrical read-out 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 read-out 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 previ-
ously 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
