Ultrafast electron-phonon scattering in antiferromagnetic Dirac semimetals

Abstract: Topological antiferromagnetic systems, which exhibit anisotropic band structures combined with complex relativistic spin structures in momentum space, have shown strong magnetoresistance effects driven by Dirac fermion characteristics. While these new antiferromagnets have been studied in transport experiments, very little is known about their spin-dependent electronic dynamics on ultrafast timescales and far-from-equilibrium behavior. This paper investigates theoretically the spin-dependent electronic dynamics due to electron-phonon scattering in a model electronic band structure that corresponds to a Dirac semimetal antiferromagnet. Following a spin conserving instantaneous excitation we obtain a change of the antiferromagnetic spin polarization due to the scattering dynamics for the site-resolved spin expectation values. This allows us to identify fingerprints of the anisotropic band structure in the carrier dynamics on ultrashort timescales.