Detecting light-induced Floquet band gaps of graphene via trARPES

TL;DR

This paper proposes a feasible method to detect light-induced topological band gaps in graphene using current trARPES technology, overcoming experimental limitations by tuning light parameters and analyzing electron distributions.

Contribution

It introduces a regime of low frequency and high amplitude circularly polarized light to observe Floquet-Bloch bands in graphene, surpassing previous resolution constraints.

Findings

Effective band gap at Dirac point exceeds Floquet zone

Distinguishes LAPE from Floquet replicas in measurements

Provides a dissipative master equation framework for analysis

Abstract

We propose a realistic regime to detect the light-induced topological band gap in graphene via time-resolved angle-resolved photoelectron spectroscopy (trARPES), that can be achieved with current technology. The direct observation of Floquet-Bloch bands in graphene is limited by low-mobility, Fourier-broadening, laser-assisted photoemission (LAPE), probe-pulse energy-resolution bounds, space-charge effects and more. We characterize a regime of low driving frequency and high amplitude of the circularly polarized light that induces an effective band gap at the Dirac point that exceeds the Floquet zone. This circumvents limitations due to energy resolutions and band broadening. The electron distribution across the Floquet replica in this limit allow for distinguishing LAPE replica from Floquet replica. We derive our results from a dissipative master equation approach that gives access to two-point correlation functions and the electron distribution relevant for trARPES measurements.