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.
Highlights
Interest in developing new platforms for efficient solar energy conversion has drawn attention to the photovoltaic properties of new materials and the physics of their lightmatter interactions
The bulk photovoltaic effect (BPVE) is a second-order nonlinear response that can be decomposed into terms that are symmetric and antisymmetric in the polarization states of the light, corresponding to a linear photogalvanic effect (LPGE) and a circular photogalvanic effect (CPGE), respectively [1]
The ballistic current is an important mechanism of the BPVE and emerges in both LPGE and CPGE [2,3,4,5], where an asymmetric distribution of photoexcited charge carriers on the conduction band is induced by electron-phonon or electron-electron scattering
Summary
Interest in developing new platforms for efficient solar energy conversion has drawn attention to the photovoltaic properties of new materials and the physics of their lightmatter interactions. But time varying electric field and a vanishing magnetic field, a time-dependent gauge transformation on the electronic wave function can bring the effective Hamiltonian back to its original unperturbed form with the addition of an electric-field-induced perturbation δH = eE(t ) · r [24,25] This form of the Hamiltonian is called the length gauge and has been used to derive expressions for the contributions to nonlinear electric currents in insulators and semimetals [6,26,27]. When mirror symmetries are broken in a chiral Weyl semimetal, point nodes with opposite topological charges are offset in energy, allowing a nonzero DC charge current to flow This can be distinguished from the extrinsic quantized circular photogalvanic effect deriving from the injection contribution to the current, which is proportional to a scattering time τ [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
