Photomagnetic-Chiral Anisotropy Mediated by Chirality-Driven Asymmetric Spin Splitting

Photomagnetic effects (PMEs), intrinsic to transition metals, arise from the interaction between light-induced angular momentum and electronic spin. These effects are suppressed in noble metals with high symmetry and electron density. Introducing chiral structures can induce photomagnetic-chiral anisotropy (PMChA) of metals by linking chirality and spin dynamics. However, a theoretical explanation remains elusive. Here, we investigated the mechanism of PMChA in tetrahelix-stacked chiral nanostructured Au chains (CNACs) using first-principles calculations. Nonequilibrium Green's function calculations reveal that chiral potentials enhance spin channel asymmetry by amplifying spin-orbit coupling (SOC)-induced spin splitting. Real-time time-dependent density functional theory simulations further identify SOC as the bridge connecting chiral spintronics to PMEs, where chirality-driven spin flips from asymmetric geometries generate opposing photomagnetic fields in materials of different handedness. These findings are consistent with experimental observations in chiral nanostructured gold films and provide theoretical guidance for designing metallic spintronic devices.