Phonon-enhanced optical spin-conductivity and spin-splitter effect in altermagnets

TL;DR

This paper demonstrates that electron-phonon interactions in altermagnets significantly enhance optical spin conductivity and the spin-splitter effect, indicating potential for improved AC spin-polarized transport in these materials.

Contribution

It introduces a detailed calculation of optical conductivity in altermagnets considering phonon scattering, revealing the positive impact of electron-phonon interactions on spin transport properties.

Findings

Electron-phonon scattering increases spin conductivity at finite frequencies.

Electron-phonon interactions enhance the spin-splitter effect.

Altermagnets with strong electron-phonon coupling are promising for AC spin transport.

Abstract

Collinear antiferromagnets with nonrelativistic spin-split bands and no net magnetization, called altermagnets, show interesting transport properties due to their unique band structure. We here compute the linear response optical conductivity of thin films of such materials in the presence of phonon scatterings. Using a tight-binding lattice model for altermagnets and the Holstein model for the phonon sector, we find that the electron-phonon scatterings can strongly increase the spin conductivity at finite frequencies. This occurs despite the fact that the self-energy describing the electron-phonon interactions is spin-independent. Interestingly, we show that electron-phonon scattering also enhances the spin-splitter effect at finite frequencies. These results suggest that altermagnets with strong electron-phonon coupling are favorable with regard to AC spin-polarized transport.