Bulk-Fermi-Arc Transition Induced Large Photogalvanic Effect in Weyl Semimetals

TL;DR

This paper predicts a novel photoinduced transition between bulk states and Fermi arcs in Weyl semimetals, leading to a large photogalvanic effect that could enable efficient terahertz photodetectors.

Contribution

It uncovers a previously unrecognized bulk-to-Fermi-arc transition causing a significant photogalvanic effect in Weyl semimetals.

Findings

Large effective shift current on Fermi arc boundaries in terahertz range

Surface photogalvanic effect can occur in WSMs without bulk shift current

Potential application in efficient terahertz photodetectors

Abstract

The surface Fermi arc, as a hallmark of Weyl semimetals (WSMs), has been well known in current research, but it remains a challenge to unveil novel phenomena associated with the Fermi arc. Here, we predict a heretofore unrecognized process in WSMs, namely, the photoinduced transition between the bulk states and the Fermi arc. We find this process is significant and can lead to a large effective three-dimensional shift current on the boundaries with the Fermi arc in wide terahertz range. Moreover, due to the low symmetry of the boundaries, the surface photogalvanic effect predicted here can appear in a large class of WSMs that do not have bulk shift current. Hence, our work not only unveils a hidden photogalvanic effect in WSMs but also suggests that all the WSMs are promising material candidates for developing efficient terahertz photodetectors.