Spectroscopic Characterization of Gapped Graphene in the Presence of Circularly Polarized Light

TL;DR

This paper investigates how circularly polarized light induces an energy gap in graphene and alters its plasmonic properties, affecting the energy loss of nearby charged particles.

Contribution

It provides a theoretical analysis of the effects of circularly polarized light on the plasmonic behavior of gapped graphene and its impact on energy loss mechanisms.

Findings

Energy gap increases plasmon wave number range.

Circularly polarized light modifies plasma excitations.

Enhanced stopping power for charged particles in gapped graphene.

Abstract

We present a description of the energy loss of a charged particle moving parallel to a graphene layer and graphene double layers. Specifically, we compare the stopping power of the plasma oscillations for these two configurations in the absence as well as the presence of circularly polarized light whose frequency and intensity can be varied to yield an energy gap of several hundred $\texttt{meV}$ between the valence and conduction bands. The dressed states of the Dirac electrons by the photons yield collective plasma excitations whose characteristics are qualitatively and quantitatively different from those produced by Dirac fermions in gapless graphene, due in part to the finite effective mass of the dressed electrons. For example, the range of wave numbers for undamped self-sustaining plasmons is increased as the gap is increased, thereby increasing the stopping power of graphene for some range of charged particle velocity when graphene is radiated by circularly polarized light.