Tunable Phonon-Driven Magnon Spin Currents in Altermagnets

TL;DR

This paper demonstrates that in two-dimensional altermagnets, phonon excitations can generate and control magnon spin currents with tunable properties, including symmetry and direction, enabling potential terahertz applications.

Contribution

It introduces a microscopic theory for phonon-induced magnon spin currents in altermagnets and shows how to tune these currents via phonon frequency and momentum.

Findings

Spin currents exhibit d-wave symmetry with phonon momentum.

Reversal of spin current direction is achievable by tuning phonon frequency.

Altermagnets can host tunable, coherent terahertz magnon spin currents.

Abstract

Altermagnets have recently attracted considerable interest due to their unique symmetry-governed spintronic properties. Here, we investigate phonon-induced magnon spin currents in a two-dimensional altermagnet. Starting from a microscopic theory of the coupled magnon-phonon system, we derive the nonequilibrium magnon distribution generated by selective phonon excitations. We show that the resulting spin currents exhibit a pronounced d-wave symmetry with respect to the phonon momentum. Moreover, the spin current along the altermagnetic directions can be completely reversed by tuning the phonon frequency. These findings establish altermagnets as promising platforms for realizing highly tunable, phonon-driven coherent terahertz magnon spin currents.