Metamagnetic multiband Hall effect in Ising antiferromagnet ErGa₂

Frustrated rare-earth-based intermetallics provide a promising platform for emergent magnetotransport properties through exchange coupling between conduction electrons and localized rare-earth magnetic moments. Metamagnetism, the abrupt change of magnetization under an external magnetic field, is a signature of first-order magnetic phase transitions; recently, metamagnetic transitions in frustrated rare earth intermetallics have attracted interest for their accompanying nontrivial spin structures (e.g., skyrmions) and associated nonlinear and topological Hall effects (THE). Here, we present metamagnetism-induced Hall anomalies in single-crystalline ErGa₂, which recalls features arising from the THE but wherein the strong Ising-type anisotropy of Er moments prohibits noncoplanar spin structures. We show that the observed anomalies are neither due to anomalous Hall effect nor THE; instead, can be accounted for via 4f-5d interactions which produce a band-dependent mobility modulation. This leads to a pronounced multiband Hall response across the magnetization process-a metamagnetic multiband Hall effect that resembles a topological-Hall-like response but without nontrivial origins. The present findings may be of general relevance in itinerant metamagnetic systems regardless of coplanar/noncoplanar nature of spins and are important for the accurate identification of Hall signals due to emergent magnetic fields.