Floquet Graphene Antidot Lattices

TL;DR

This paper develops a theoretical framework for Floquet graphene antidot lattices driven by circularly polarized light, revealing a rich phase diagram with tunable electronic properties and potential applications in optoelectronics.

Contribution

It introduces a non-perturbative Floquet formalism for analyzing driven graphene antidot lattices and predicts tunable electronic phases and dynamical localization effects.

Findings

Restoration of Dirac dispersion in real time.

Ability to tune quasienergy gaps with drive amplitude.

Emergence of Floquet semi-Dirac and localized bands.

Abstract

We establish the theoretical foundation of the Floquet graphene antidot lattice, whereby massless Dirac fermions are driven periodically by a circularly polarized electromagnetic field, while having their motion excluded from an array of nanoholes. The properties of interest are encoded in the quasienergy spectra, which are computed non-perturbatively within the Floquet formalism. We find that a rich Floquet phase diagram emerges as the amplitude of the drive field is varied. Notably, the Dirac dispersion can be restored in real time relative to the gapped equilibrium state, which may enable the creation of an optoelectronic switch or a dynamically tunable electronic waveguide. As the amplitude is increased, the ability to shift the quasienergy gap between high-symmetry points can change which crystal momenta dominate in the scattering processes relevant to electronic transport and optical emission. Furthermore, the bands can be flattened near the $\Gamma$ point, which is indicative of selective dynamical localization. Lastly, quadratic and linear dispersions emerge in orthogonal directions at the $M$ point, signaling a Floquet semi-Dirac material. Importantly, all our predictions are valid for experimentally accessible near-IR radiation, which corresponds to the above bandwidth limit for the graphene antidot lattice. Cycling between engineered Floquet electronic phases may play a key role in the development of next-generation on-chip devices for optoelectronic applications.