Intrinsic Fermi Surface Contribution to the Bulk Photovoltaic Effect

TL;DR

This paper reveals a new intrinsic Fermi surface contribution to the bulk photovoltaic effect in metals, derived from photoinduced electronic transitions, with implications for topological materials like Weyl semimetals.

Contribution

It introduces a comprehensive formula for the Fermi surface contribution to the nonlinear photocurrent, including effects in Weyl semimetals and classification based on light polarization.

Findings

Fermi surface contribution is proportional to the driving frequency at low frequencies.

The sign of the response is determined by the topological charge of Weyl nodes.

Magnitude of this effect is comparable to the quantized circular photogalvanic effect.

Abstract

We study the Fermi surface contribution to the nonlinear DC photocurrent at quadratic order in a spatially uniform optical field in the ultra-clean limit. In addition to shift and injection current, we find that polarized light incident on a metallic system generates an intrinsic contribution to the bulk photovoltaic effect deriving from photoinduced electronic transitions on the Fermi surface. In {velocity} gauge, this contribution originates in both the coherent band off-diagonal and diagonal parts of the density matrix, describing respectively, the coherent wave function evolution and the carrier dynamics of an excited population. We derive a formula for the intrinsic Fermi surface contribution for a time-reversal invariant chiral Weyl semimetal illuminated with circularly-polarized light. At low frequency, this response is proportional to the frequency of the driving field, with its sign determined by the topological charge of the Weyl nodes and with its magnitude being comparable to the recently discovered quantized circular photogalvanic effect. Our work presents a complete derivation for all contributions to nonlinear DC photocurrent and classify them according to the polarization of light in the presence and absence of TRS.