Optically Generated Spin Current in Two-Dimensional\nMetallic 2H-MX<sub>2</sub> (M = Nb and Ta and X= S and Se): Role of\nAnisotropic Spin Splitting

Metallic\ntwo-dimensional (2D) transition-metal dichalcogenides\n(TMDs) (MX<sub>2</sub>, where M = Nb and Ta and X = S and Se) exhibit\nIsing-type spin–orbit coupling (SOC), acting as an effective\nZeeman field. The Ising-type SOC can induce topological properties\nsuch as finite spin Berry curvature (SBC) in the whole Brillouin zone\n(BZ). Here, utilizing density functional theory, we investigate the\nspin-dependent optical conductivity of metallic TMD monolayers. We\nobserve a peak in the SBC at the center of the BZ, where no Fermi\nline exists. This peak arises due to the combined effects of SOC and\nanisotropic spin splitting in the monolayers of NbSe<sub>2</sub> and\nTaSe<sub>2</sub>. Finally, we demonstrate how this peak value of SBC\nat the center of the BZ influences the pure spin Hall current in these\nmonolayers under light irradiation. This study holds potential interest\nfor experimental efforts aimed at designing systems to harvest spin\ncurrents through light irradiation in metallic 2D TMDs.