Giant magneto-optical effect in the magnetic Weyl semimetal Co₃Sn₂S₂

The search for the topological materials has rapidly developed and novel phase of matter has been extensively proposed in recent years. In particular, the discovery of the Weyl semimetal (WSM), which has a pair of the Wey points with intense Berry curvature, is the important advance in this field. While the WSM shows various giant/functional electromagnetic phenomena such as the nonlinear optical effects and anomalous Hall effect (AHE), the direct evidence that the Weyl point plays the decisive role for those phenomena is still lacking. In this presentation, we will report the magneto-optical study on the recently discovered magnetic WSM Co₃Sn₂S₂ with the giant AHE. The magneto-optical Kerr effect (MOKE) and first-principles calculations reveal that the optical Hall conductivity spectra are significantly dominated by the interband transition upon the nodal ring structures and the Weyl points. This observation demonstrates that those electronic structures play the decisive roles for the giant intrinsic AHE. We will also discuss the MOKE, which is exceptionally large compared with the conventional ferromagnetic metals.