Anomalous and Topological Hall Effects in Antiferromagnetic EuSn2As2 Nanostructures

TL;DR

This study explores magnetotransport phenomena in exfoliated EuSn2As2 nanostructures, revealing anomalous and topological Hall effects linked to chiral spin textures and magnetic states in a 3D topological insulator.

Contribution

It provides new insights into the magnetic and topological Hall effects in EuSn2As2 nanostructures, highlighting the presence of chiral spin textures in magnetic 3D topological insulators.

Findings

Observation of anomalous Hall effect in CAF state

Detection of topological Hall effect due to chiral spin textures

Evidence of non-linear Hall response from multiple electronic bands

Abstract

We investigate magnetotransport in exfoliated nanostructures of the candidate magnetic 3D topological insulator $\mathrm{EuSn_{2}As_{2}}$. Similar to macroscopic single crystals, the negative magnetoresistance observed below the N\'eel temperature ($T_N$ = 24 K) is related to the canted antiferromagnetic state (CAF) of an easy-plane antiferromagnet (AFM), with an increase of the saturation field when tilting the applied magnetic field away from the (ab) plane ($\mu_{0} H^{c}_{s}$ = 4.9 T, $\mu_{0} H^{ab}_{s}$ = 3.6 T). Higher-accuracy measurements in nanostructures up to 14 T further evidence a non-linear normal Hall response due to several electronic bands. Interestingly, the transverse resistance due to magnetism reveals an anomalous Hall effect in the CAF state, but also a topological Hall effect due to chiral spin textures, as found in AFM or helical magnets. The presence of real-space chiral spin texture, already reported in another magnetic topological insulator, $\mathrm{MnBi_{2}Te_{4}}$, could be a characteristic generally appearing in magnetic 3D topological insulators.