Colossal anomalous Hall conductivity in half-metallic material Fe-doped CoS₂

While it is well-established that the intrinsic anomalous Hall conductivity (AHC) arises from Berry curvature (BC) induced by spin-orbit gapped band anti-crossing, reported AHC values typically fall within the range of 100 to 1000 Ω^-1cm^-1. The primary reason for the often modest AHC lies in the cancellation of BC sources in the momentum space. This study delves into the AHC of cobalt disulfides (CoS₂), revealing resonant behavior as the chemical potential approaches the middle of the gap through varying Fe-doping levels. Co_0.95Fe_0.05S₂, in particular, exhibits a resonant peak of 2507 Ω^-1cm^-1, more than four times larger than that of CoS₂. Our density functional theory and tight-binding analyses trace this substantial AHC to four spin-polarized massive Dirac dispersions in the k_z = 0 plane of the Brillouin zone, positioned just below the Fermi level. The observed colossal AHC stems from the four BC sources, a consequence of d-wave-like spin-orbit coupling among spin-polarized e_g orbitals with the same sign, preventing cancellation. This result unveils the mechanism behind the significantly tunable AHC in CoS₂ and provides insights into a strategy for identifying similar materials.