Anomalous Hall effect triggered by pressure-induced magnetic phase transition in $\alpha$-Mn

TL;DR

This study discovers a pressure-induced magnetic phase transition in $ ext{α}$-Mn that triggers a large anomalous Hall effect, highlighting the role of magnetic symmetry and Berry curvature in this phenomenon.

Contribution

It provides the first evidence linking magnetic phase transitions under pressure to large AHE in elemental $ ext{α}$-Mn, emphasizing the importance of magnetic symmetry and Berry curvature.

Findings

Large AHE observed in high-pressure ferromagnetic phase

AHE absent in ambient-pressure antiferromagnetic phase

Magnetic structure symmetry governs the emergence of AHE

Abstract

Recent interest in topological nature in condensed matter physics has revealed the essential role of Berry curvature in anomalous Hall effect (AHE). However, since large Hall response originating from Berry curvature has been reported in quite limited materials, the detailed mechanism remains unclear at present. Here, we report the discovery of a large AHE triggered by a pressure-induced magnetic phase transition in elemental $\alpha$-Mn. The AHE is absent in the non-collinear antiferromagnetic phase at ambient pressure, whereas a large AHE is observed in the weak ferromagnetic phase under high pressure despite the small averaged moment of $\sim 0.02 \mu_B$/Mn. Our results indicate that the emergence of the AHE in $\alpha$-Mn is governed by the symmetry of the underlying magnetic structure, providing a direct evidence of a switch between a zero and non-zero contribution of the Berry curvature across the phase boundary. $\alpha$-Mn can be an elemental and tunable platform to reveal the role of Berry curvature in AHE.