Scaling behaviors in thermally driven topological Hall effect*

Topological spin textures such as magnetic skyrmions are robust to external perturbations due to their topological protection and therefore show great potential in low-power spintronics applications. A peak in the Hall effect resistance of a magnetic system, referred to as the topological Hall effect (THE), can be a signature for the existence of topological spin textures. However, some studies solely use the THE to claim the existence of textures like skyrmions due to the limitations of magnetic imaging at the nanometer-length scale. In this talk, we demonstrate an alternative explanation for the THE that does not invoke skyrmions. We observe a Hall effect peak in the paramagnetic regime of lithium aluminum ferrite (LAFO) films interfaced with Pt, whose onset temperature matches well with LAFO’s Curie temperature T_c. We thus postulate that the THE originates from thermally driven topology as opposed to long-range topological order. We reveal a power law scaling in the THE as a function of (T-T_c) that extends far beyond T_c, as well as a cosθ/B relation as a function of the external magnetic field B and the angle at which it is applied θ, and try to explore the mechanisms governing these observations through Monte Carlo simulations. This work suggests that thermally driven topology can give rise to a THE and urges caution when drawing skyrmion-related conclusions simply from Hall effect features.