title: Giant Hall Photoconductivity in Narrow-Gapped Dirac Materials.
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 6 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.
authors.affiliation: Institute of High Performance Computing, Agency for Science, Technology, and Research, Singapore 138632.|Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371.
authors.forename: Justin C W
authors.initials: JC
authors.lastname: Song
authors.affiliation: Department of Electrical and Computer Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.|Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.|Department of Physics, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Kats
keywords: Berry curvature; photoconductivity; two-dimensional materials