Ina Park, Turan Birol, Antoine Georges, Rafael M. Fernandes
As a material that undergoes a metal-insulator transition inside the altermagnetic phase, NiS${}_{2\ensuremath{-}x}$Se${}_{x}$ provides an ideal framework to elucidate the interplay between electronic correlations and altermagnetism. This work disentangles the impact of static and dynamic correlations on altermagnetic properties by systematically comparing DFT, DFT+$U$, and DFT+DMFT calculations on NiS${}_{2\ensuremath{-}x}$Se${}_{x}$. The key result is that dynamical correlations not only modify the magnitude of the spin splitting but also promote a sharp asymmetry in the lifetimes of spin-up and spin-down quasiparticles, which is further amplified by multi-orbital Hund's correlation effects.