Electric and spin-valley currents induced by structured light in 2D Dirac materials

TL;DR

This paper develops a theoretical framework to analyze how structured light induces electric and spin-valley currents in 2D Dirac materials, revealing mechanisms and providing analytical expressions for current generation.

Contribution

It introduces a comprehensive kinetic theory for photoinduced currents in 2D Dirac materials under structured light, including new mechanisms related to optical alignment and photon drags.

Findings

Derived general expressions for current density and generation rates.

Identified mechanisms of current formation related to light polarization.

Applied theory to TMDC layers and graphene with polarization gratings.

Abstract

Structured optical fields can be used for the injection and control of charge and spin-valley currents. Here, we present a systematical study of these phenomena for interband absorption of structured light in 2D Dirac materials. We derive general expressions for the current density and the quasi-classical generation rate of photoelectrons in the momentum, coordinate, and spin-valley spaces. We reveal mechanisms of the current formation determined by the local and non-local contributions to the optical generation, including the mechanisms related to optical alignment of electron momenta by linearly polarized light, optical orientation by circularly polarized light, and the class of charge and spin-valley photon drags sensitive to the phase and polarization profiles of the optical field. We develop a kinetic theory of electric and spin-valley currents driven by the optical field with spatially inhomogeneous intensity, polarization, and phase and obtain analytical expressions for the current contributions. The theory is applied to analyze the photocurrents emerging in TMDC layers and graphene excited by polarization gratings.