Observation of Switchable Chiral Magnons in an Altermagnet

TL;DR

This paper reports the direct observation of switchable chiral magnons in an altermagnet, MnTe, demonstrating a new, magnetically controllable platform for efficient magnon-based spin transport without stray fields.

Contribution

First direct detection of chiral magnons in an altermagnet and demonstration of reversible magnetic-field control of magnon chirality.

Findings

Chiral magnons observed in MnTe via polarized inelastic neutron scattering.

Magnon chirality can be reversibly switched by magnetic field.

Altermagnets provide a stray-field-free platform for magnonics.

Abstract

Chiral magnons, the quanta of handed spin waves, transport spin angular momentum without energy loss due to Joule heating. The recently discovered altermagnets were proposed to host chiral magnons arising from a non-relativistic exchange mechanism, similar to that in ferromagnets but without net magnetization, offering a stray-field-free platform for efficient magnon spin-current manipulation. In this work, we directly observed chiral magnons in the altermagnetic prototype MnTe using polarized inelastic neutron scattering. Furthermore, the magnon chirality was found to be reversibly switched by magnetic-field control, establishing a robust foundation for functional altermagnetic magnonics.