Light-induced anomalous Hall conductivity in the massive three-dimensional Dirac semimetal Co₃⁢Sn₂⁢S₂

Weyl semimetals can emerge from Dirac semimetals when the time-reversal or spatial-inversion symmetries are broken. Recently, it has been proposed based on Floquet theory that Dirac semimetals can be converted into Weyl semimetals even by shining circularly polarized light (CPL). Here we have investigated the possibility of such a Dirac-Weyl conversion by measuring the CPL-induced anomalous Hall conductivity (AHC) in a massive 3D Dirac semimetal Co₃⁢Sn₂⁢S₂ in the paramagnetic phase using ultrafast midinfrared pump-terahertz Faraday rotation probe spectroscopy. We find that the field-strength and driving frequency dependence of the observed AHC is well accounted for by CPL-induced nonzero Berry curvature associated with the splitting of the Dirac bands as predicted by the Floquet theory. As a result, the estimated splitting of the Dirac bands reaches about 60% of the mass gap and the calculated CPL-induced AHC quantitatively reproduces the experimental observation, demonstrating a promising route toward the realization of Floquet-Weyl states from massive Dirac semimetals.. Authors: Yoshikawa, Naotaka [University of Tokyo (Japan)] (ORCID:0000000222918002); Okumura, Shun [University of Tokyo (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako (Japan)]; Hirai, Yoshua [University of Tokyo (Japan)] (ORCID:0000000273428185); Ogawa, Kazuma [University of Tokyo (Japan)] (ORCID:0000000203575235); Fujiwara, Kohei [Tohoku University, Sendai (Japan)]. DOE Contract: SC0010821. Subjects: 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Anomalous Hall effect; Bloch-Floquet theorem; Dirac semimetal; Optical-pump terahertz-probe spectroscopy; Topological phases of matter; Weyl semimetal