Weak Ferromagnetism in Altermagnets from Alternating $g$-Tensor Anisotropy

TL;DR

This paper proposes a theoretical mechanism where alternating $g$-tensor anisotropy induces weak ferromagnetism in altermagnets, providing new insights into their magnetic properties without relying on Dzyaloshinskii-Moriya interactions.

Contribution

It introduces a novel orbital-based mechanism for weak ferromagnetism in altermagnets, expanding understanding of their magnetic behavior.

Findings

Alternating $g$-tensor anisotropy can induce weak ferromagnetism.

The mechanism applies to both collinear and noncollinear altermagnets.

Provides new ways to manipulate magnetic states in altermagnets.

Abstract

Altermagnets are magnetic materials with antiferromagnetic spin ordering but exhibit ferromagnetic properties. Understanding the microscopic origin of the latter is a central problem. Ferromagnet-like properties such as the anomalous Hall effect are linked with weak ferromagnetism, whose microscopic origin in altermagnets remains unclear however. We show theoretically that the alternating $g$-tensor anisotropy in altermagnets can induce weak ferromagnetism even when the Dzyaloshinskii-Moriya interaction is forbidden. We demonstrate this mechanism to explain weak ferromagnetism for both collinear and noncollinear spin altermagnets. Our findings provide new insights into the origin of weak ferromagnetism and suggest orbital-based ways for manipulating magnetic configurations in altermagnets.