Efficient generation of spin currents in altermagnets via magnon drag

Altermagnets, a recently identified class of magnetic materials, possess a spin-split Fermi surface that results in the so-called spin-splitter effect, enabling the generation of a spin current transverse to the injection direction and whose polarization lies along the N\'eel vector. In this study, we investigate how magnons interact with electrons in an altermagnetic metal. We find that while the electron-magnon interaction does not perturb the magnon dispersion, a charge current flowing in the material can induce a transverse magnon spin current, analogous to the electronic spin-splitter effect. This spin current possesses both electronic and magnonic characteristics, i.e., a chemical potential dependence and a strong temperature dependence. This effect realizes the efficient generation of spin currents via magnons without depending on the material's spin-orbit coupling.