Disentangling the Competing Mechanisms of Light-Induced Anomalous Hall Conductivity in Three-Dimensional Dirac Semimetal

We experimentally elucidate the origin of the anomalous Hall conductivity in a three-dimensional Dirac semimetal, Cd3As2, driven by circularly polarized light. Using time-resolved terahertz Faraday rotation spectroscopy, we determine the transient Hall conductivity spectrum with special attention to its sign. Our results clearly show the dominance of direct photocurrent generation assisted by the terahertz electric field. The contribution from the Floquet-Weyl nodes is found to be minor when the driving light is in resonance with interband transitions. We develop a generally applicable classification of microscopic mechanisms of light-induced anomalous Hall conductivity.

Automated summary

We experimentally investigate the origin of the anomalous Hall conductivity in Cd3As2, a three-dimensional Dirac semimetal, driven by circularly polarized light. Our results show that direct photocurrent generation assisted by the terahertz electric field dominates, while the contribution from the Floquet-Weyl nodes is minor when the driving light is in resonance with interband transitions. We propose a generally applicable classification of microscopic mechanisms for light-induced anomalous Hall conductivity.