Emergence of a spin Hall topological Hall effect in the non-collinear phase of the ferrimagnetic insulator terbium-iron garnet

TL;DR

This study demonstrates a spin Hall topological Hall effect in non-collinear ferrimagnetic phases of terbium-iron garnet, linked to complex magnetic textures near the compensation temperature.

Contribution

It reveals the emergence of a topological Hall-like signal associated with non-collinear magnetic textures in REIGs, expanding understanding of topological effects in ferrimagnetic insulators.

Findings

Topological Hall-like signal appears near compensation temperature.

Kerr microscopy shows a non-collinear multidomain state correlating with the Hall signal.

The effect is not explained by a multi-anomalous-Hall-effect model.

Abstract

Magnetic compensation in rare-earth iron garnets (REIGs) offers a unique setting for which competing sublattice moments can give rise to non-collinear (canted) magnetic configurations, in which the sublattice magnetizations are not aligned with each other or with the external magnetic field. We show that this compensation regime can also host non-trivial magnetic textures. To explore this behavior, we investigated (111)-oriented epitaxial Tb$_3$Fe$_5$O$_{12}$/Pt heterostructures across the compensation temperature region using combined transverse magneto-transport and polar Kerr microscopy. Notably, we observe a topological Hall-like signal in the vicinity of the compensation temperature, a feature often interpreted as evidence for skyrmions in the absence of direct imaging. Here, in contrast, complementary Kerr microscopy reveals instead a non-collinear multidomain state which collapses outside the compensation regime, correlating directly with the appearance and disappearance of the spin Hall topological Hall effect (SH-THE) signal. These observations cannot be accounted for by a simple multi-anomalous-Hall-effect model, ruling out common artifacts as the origin, but indicate the presence of a topologically non-trivial contribution to the Hall response. These results establish strained REIG films as a tunable platform for exploring topological responses arising from compensation-driven non-collinear ferrimagnetic phases.