F. SchilberthM.-C. JiangS. MinamiM. A. KassemF. MayrT. KoretsuneY. TabataT. WakiH. NakamuraGUANG-YU GUOR. AritaI. KézsmárkiS. Bordács2024-10-152024-10-152023-06-27https://scholars.lib.ntu.edu.tw/handle/123456789/722081Giant anomalous Hall effect (AHE) and magneto-optical activity can emerge in magnets with topologically nontrivial degeneracies. However, identifying the specific band-structure features such as Weyl points, nodal lines, or planes which generate the anomalous response is a challenging issue. Since the low-energy interband transitions can govern the static AHE, we addressed this question in the prototypical magnetic Weyl semimetal Co3Sn2S2 also hosting nodal lines by broadband polarized reflectivity and magneto-optical Kerr effect spectroscopy with a focus on the far-infrared range. In the linear dichroism spectrum we observe a strong resonance at 40 meV, which also appears in the optical Hall conductivity and primarily determines the static AHE, and thus confirms its intrinsic origin. Our material-specific theory reproduces the experimental data remarkably well and shows that strongly tilted nodal-line segments around the Fermi energy generate the resonance. While the Weyl points only give vanishing contributions, these segments of the nodal lines gapped by the spin-orbit coupling dominate the low-energy optical response and generate the giant AHE.[SDGs]SDG7journal article10.1103/physrevb.107.214441