Floquet control of electron and exciton transport in Kekulé-distorted graphene
Phys. Rev. B 114, 034306 – Published 13 July, 2026
DOI: https://doi.org/10.1103/6nc8-5vtd
Abstract
This work investigates the Floquet dynamics of electrons and excitons (particle-hole pairs) in a Dirac material referred to as Kekulé-distorted graphene. Specifically, we examine the role played by a high frequency driving electromagnetic field on the tunneling and blocking by a potential barrier on both the charged single particles as well as the neutral composite particles. We demonstrate that the small effective masses of the electron and hole for the energy spectrum of this Kekulé-distorted graphene leads to practically almost perfect transmission across a symmetric potential barrier for any angle of incidence of impinging excitons. However, this unexpected Klein paradox for excitons does not hold for the single-particle electrons. For individual electrons, tunneling at normal incidence becomes almost perfect for the small energy gap which opens up due to the applied high frequency irradiation. Whenever the gap is increased for larger values of the irradiation parameter, the perfect transmission is noticeably suppressed. The reduced total transmission coefficient at incident angle other than head-on for electrons due to Kekulé distortion is more suppressed in the presence of irradiation. Additionally, we calculate and investigate the exciton binding energy since the quantum tunneling of a bound electron-hole pair across a potential barrier is governed by its mass measured in the center of mass and binding energy of the composite pair. Thus, irradiation with circularly polarized light fundamentally modifies exciton formation, coherence and transport properties, thereby producing unusual topological behaviors. These behaviors are unlike conventional Dirac materials. Possible technical applications of the results arising from our investigation include valleytronics due to the folding of the valleys, thereby making intervalley coupling feasible. Other practical applications include optoelectronics due to Floquet tuning of energy spectrum and transport properties.
