Multiferroic collinear antiferromagnet with hidden altermagnetic split

TL;DR

This paper reveals that certain conventional antiferromagnets with a nonzero propagation vector exhibit hidden altermagnetic spin splitting and symmetry breaking, offering new avenues for spintronic material design.

Contribution

It demonstrates that conventional antiferromagnets with a nonzero Q vector can have hidden altermagnetic effects due to symmetry breaking, expanding the understanding of spin splitting mechanisms.

Findings

First-principles calculations on MnS2 show hidden altermagnetic spin splitting.

Identification of macroscopic symmetry breaking without lifting spin degeneracy.

Potential for novel spintronic applications based on these properties.

Abstract

Altermagnets exhibit nonrelativistic spin splitting due to the breaking of time-reversal symmetry and have been garnering significant attention as promising materials for spintronic applications. In contrast, conventional antiferromagnets without spin splitting seem not to have any symmetry breaking and have drawn less attention. However, we show that conventional antiferromagnets with a nonzero propagation vector (Q vector) bring about nontrivial symmetry breakings. The incompatibility between the Q vector and nonsymmorphic symmetry leads to macroscopic symmetry breaking without lifting spin degeneracy. Moreover, the hidden altermagnetic spin splitting in the electronic structure gives rise to various emergent responses. To examine our prediction, we perform first-principles calculations for MnS2 and investigate its multiferroic properties, such as nonlinear transport and optical activity. Our findings reveal unique properties in conventional antiferromagnets, providing another perspective for designing spintronic materials.