Interpretation of experimental evidence of the topological Hall effect

TL;DR

This paper challenges the interpretation of the topological Hall effect as definitive evidence of skyrmions, showing that similar signals can arise from heterogeneous ferromagnets with opposing Hall effects, thus questioning previous assumptions.

Contribution

It reveals that non-monotonic Hall signals attributed to skyrmions can also originate from material heterogeneity and opposing Hall effects, providing a new perspective on experimental interpretations.

Findings

Similar Hall features occur in heterogeneous ferromagnets.

Opposing Hall effects in different components can mimic topological Hall signals.

Relevance of this mechanism to previous data is discussed.

Abstract

The topological Hall effect in magnetic materials is considered the ultimate trademark of the skyrmion phase. The phenomenon is identified by distinct non-monotonic features in the Hall effect signal presumed to be the evidence of the topological origin. It is demonstrated here that similar features, unrelated to the skyrmion physics, arise in heterogeneous ferromagnets when components of the material exhibit the extraordinary Hall effect with opposite polarities. Relevance of this mechanism to the published data is discussed.