Topological Hall Effect Driven by Short-Range Magnetic Orders in EuZn$_2$As$_2$

TL;DR

This study reveals that EuZn₂As₂ exhibits a topological Hall effect driven by short-range magnetic orders coexisting with long-range antiferromagnetic order, highlighting the role of magnetic correlations in topological transport phenomena.

Contribution

It demonstrates the presence of short-range magnetic orders influencing topological Hall effects in EuZn₂As₂, a centrosymmetric compound, expanding understanding of magnetic contributions to topological transport.

Findings

Observation of anomalous Hall effect above the AF transition.

Coexistence of ferromagnetic short-range order with long-range AF order.

Evidence of non-zero spin chirality and Berry curvature in EuZn₂As₂.

Abstract

Short-range (SR) magnetic orders such as magnetic glass orders or fluctuations in a quantum system usually host exotic states or critical behaviors. As the long-range (LR) magnetic orders, SR magnetic orders can also break time-reversal symmetry and drive the non-zero Berry curvature leading to novel transport properties. In this work, we report that in EuZn$_2$As$_2$ compound, besides the LR A-type antiferromagnetic (AF) order, the SR magnetic order is observed in a wide temperature region. The magnetization measurements and electron spin resonance (ESR) measurements reveal the ferromagnetic (FM) correlations for this SR magnetic order which results in an obvious anomalous Hall effect above the AF transition. Moreover the ESR results reveal that this FM SR order coexists with LR AF order exhibiting anisotropic magnetic correlations below the AF transition. The interactions of LR and SR magnetism evolving with temperature and field can host non-zero spin charility and berry curvature leading the additional topological Hall contribution even in a centrosymmetric simple AF system. Our results indicate that EuZn$_2$As$_2$ is a fertile platform to investigate exotic magnetic and electronic states.