Giant Anomalous Hall Effect in the Chiral Antiferromagnet Mn3Ge

TL;DR

This paper reports the discovery of a giant anomalous Hall effect in the chiral antiferromagnet Mn3Ge, demonstrating significant potential for antiferromagnetic spintronic applications due to its large Hall conductivity and controllable magnetic response.

Contribution

The study presents the first observation of a giant anomalous Hall effect in Mn3Ge, expanding understanding of Hall phenomena in antiferromagnets and highlighting its potential for technological applications.

Findings

Mn3Ge exhibits a giant anomalous Hall conductivity of ~60 S/cm at room temperature.

The Hall conductivity reaches ~380 S/cm at 5 K in zero field.

The AHE shows a sign reversal with small magnetic field rotation, indicating controllability.

Abstract

The external field control of antiferromagnetism is a significant subject both for basic science and technological applications. As a useful macroscopic response to detect magnetic states, the anomalous Hall effect (AHE) is known for ferromagnets, but it has never been observed in antiferromagnets until the recent discovery in Mn3Sn. Here we report another example of the AHE in a related antiferromagnet, namely, in the hexagonal chiral antiferromagnet Mn3Ge. Our single-crystal study reveals that Mn3Ge exhibits a giant anomalous Hall conductivity $|\sigma_{xz}|$ ~ 60 per ohm per cm at room temperature and approximately 380 per ohm per cm at 5 K in zero field, reaching nearly half of the value expected for the quantum Hall effect per atomic layer with Chern number of unity. Our detailed analyses on the anisotropic Hall conductivity indicate that in comparison with the in-plane-field components $|\sigma_{xz}|$ and $|\sigma_{zy}|$, which are very large and nearly comparable in size, we find $|\sigma_{yx}|$ obtained in the field along the c axis is found to be much smaller. The anomalous Hall effect shows a sign reversal with the rotation of a small magnetic field less than 0.1 T. The soft response of the AHE to magnetic field should be useful for applications, for example, to develop switching and memory devices based on antiferromagnets.