Giant spatial anisotropy of magnon lifetime in altermagnets

TL;DR

This paper reveals a giant spatial anisotropy in magnon lifetimes in altermagnets, where magnon propagation is directionally suppressed due to coupling with Stoner modes, significantly affecting transport properties and potential spintronic uses.

Contribution

It uncovers the strong directional dependence of magnon lifetimes in altermagnets and the role of Stoner modes in suppressing magnon propagation along specific directions.

Findings

Magnon lifetimes in altermagnets are highly anisotropic.

Coupling to Stoner modes can completely suppress magnon propagation.

The anisotropy impacts electronic, spin, and energy transport properties.

Abstract

Altermagnets are a new class of magnetic materials with zero net magnetization (like antiferromagnets) but spin-split electronic bands (like ferromagnets) over a fraction of reciprocal space. As in antiferromagnets, magnons in altermagnets come in two flavours, that either add one or remove one unit of spin to the $S=0$ ground state. However, in altermagnets these two magnon modes are non-degenerate along some directions in reciprocal space. Here we show that the lifetime of altermagnetic magnons has a very strong dependence on both flavour and direction. Strikingly, coupling to Stoner modes leads to a complete suppression of magnon propagation along selected spatial directions. This giant anisotropy will impact electronic, spin, and energy transport properties and may be exploited in spintronic applications.