Three-dimensional real-space electron dynamics in graphene driven by strong laser fields

TL;DR

This study uses time-dependent density functional theory to explore 3D electron dynamics in graphene under strong laser fields, revealing out-of-plane current distributions and validating the two-level system approximation with experimental relevance.

Contribution

It provides a first-principles 3D analysis of laser-driven electron currents in graphene, highlighting out-of-plane effects and confirming previous theoretical predictions.

Findings

Reproduction of current reversal phenomena

Validation of two-level system approximation

Discovery of out-of-plane current concentration

Abstract

We theoretically investigate the three-dimensional (3D) electron dynamics of graphene in real space under strong laser fields using time-dependent density functional theory (TDDFT). We successfully reproduce the reversal of current direction originating from the cancellation of two oppositely directed residual currents, as previously predicted by Morimoto et al. [Y. Morimoto et al., New J. Phys. 24, 033051 (2022)]. By distinguishing contributions from individual orbitals, our results validate the two-level system approximation and also emphasize that the first-principles approach agrees better with experimental results for light-driven residual current, especially in extremely strong fields. Furthermore, our 3D model reveals that the real-space atomic-scale current induced by strong laser fields is concentrated slightly above and below the graphene basal plane, rather than strictly within it. The two oppositely directed currents exhibit a pronounced height separation in the out-of-plane direction, indicating that the ring current is not confined to the graphene plane but forms a rotating 3D circulation loop which is absent in the reduced-dimensional model.