Dynamic paramagnon-polarons in altermagnets

Altermagnetic states are qualitatively different from ferromagnetic and antiferromagnetic ones, as they are invariant under a combination of rotation and time reversal. The unique properties afforded by such symmetries have attracted significant attention by the community. Here, the authors unearth an unusual dynamic coupling that exists between the altermagnetic and lattice degrees of freedom, which resembles the Hall viscosity. This effect results in a hybridization between altermagnetic and phonon modes, enabling one to directly probe altermagnetic excitations in the phonon spectrum.