Field-induced Topological Hall effect in antiferromagnetic axion insulator candidate EuIn$_2$As$_2$

TL;DR

This study reveals the presence of a topological Hall effect in EuIn₂As₂, an antiferromagnetic axion insulator candidate, driven by field-induced noncoplanar spin textures affecting its magnetotransport properties.

Contribution

It provides the first detailed experimental investigation of magnetotransport in EuIn₂As₂, demonstrating the emergence of topological Hall effect linked to magnetic field-induced spin textures.

Findings

Observation of anomalous Hall effect due to Berry curvature

Detection of large topological Hall effect from noncoplanar spins

Magnetotransport strongly influenced by Eu magnetic moments

Abstract

The magnetic topological materials have attracted significant attention due to their potential realization of variety of novel quantum phenomena. EuIn$_2$As$_2$ has recently been theoretically recognized as a long awaited intrinsic antiferromagnetic bulk axion insulator. However, the experimental study on transport properties arising from the topological states in this material is scarce. In this paper, we perform the detailed magnetoresistance (MR) and Hall measurements to study the magnetotransport properties of this material. We find that the transport is strongly influenced by the spin configuration of the Eu moments from the concomitant change in the field dependence of the MR and that of the magnetization below the N\'eel temperature. Most importantly, an anomalous Hall effect (AHE) and a large topological Hall effect (THE) are observed. We suggest that the AHE is originated from a nonvanishing net Berry curvature due to the helical spin structure and that the THE is attributed to the formation of a noncoplanar spin texture with a finite scalar spin chirality induced by the external magnetic field in EuIn$_2$As$_2$. Our studies provide a platform to understand the influence of the interplay between the topology of electronic bands and the field-induced magnetic structure on magnetoelectric transport properties. In addition, our observations give a hint to realize axion insulator states and high-order topological insulator states through manipulating the magnetic state of EuIn$_2$As$_2$.