Giant Hall photoconductivity in narrow-gapped Dirac materials

TL;DR

This paper demonstrates that narrow-gapped Dirac materials exhibit a giant, helicity-dependent Hall photoconductivity driven by Berry curvature, significantly enhancing infrared and terahertz optoelectronic responses.

Contribution

It reveals a new mechanism for photoconductivity enhancement in gapped Dirac materials due to Berry curvature effects, especially under circularly polarized light.

Findings

Hall photoconductivity is greatly enhanced in narrow-gapped Dirac materials.

The effect is helicity-dependent and dominates the photoconductivity in the Hall regime.

Enhancement of Hall conductivity per incident irradiance by up to six orders of magnitude.

Abstract

Carrier dynamics acquire a new character in the presence of Bloch-band Berry curvature, which naturally arises in gapped Dirac materials (GDMs). Here we argue that photoresponse in GDMs with small band gaps is dramatically enhanced by Berry curvature. This manifests in a giant and saturable Hall photoconductivity when illuminated by circularly polarized light. Unlike Hall motion arising from a Lorentz force in a magnetic field, which impedes longitudinal carrier motion, Hall photoconductivity arising from Berry curvature can boost longitudinal carrier transport. In GDMs, this results in a helicity-dependent photoresponse in the Hall regime, where photoconductivity is dominated by its Hall component. We find that the induced Hall conductivity per incident irradiance is enhanced by up to six orders of magnitude when moving from the visible regime (with corresponding band gaps) to the far infrared. These results suggest that narrow-gap GDMs are an ideal test-bed for the unique physics that arise in the presence of Berry curvature, and open a new avenue for infrared and terahertz optoelectronics.