Quasi-energy spectra of graphene dots under intense ac field: field anisotropy and photon dressed quantum rings

TL;DR

This paper investigates how intense ac fields and magnetic fields affect the electronic properties of graphene quantum dots, revealing field-induced quantum ring behavior and anisotropic signatures in their spectra.

Contribution

It introduces a Fourier-Floquet approach to show that ac fields induce quantum ring features in anisotropic graphene dots, a novel insight into their field-dependent electronic structure.

Findings

Field polarization affects the quasi-density of states.

An ac field induces quantum ring-like minibands.

Electronic spectra show orientation-dependent miniband formation.

Abstract

A graphene quantum dot under intense ac field and static low magnetic field is investigated. From a tight-binding perspective, applying a Fourier-Floquet transformation and renormalization process, we observe that graphene -intrinsically anisotropic- reveals field polarization signatures in the quasi-density of states. For the ac field polarized along the armchair direction, the dressed electronic structure shows an emergent property: an ac field induced quantum ring. This is inferred by the orientation-dependent formation of a miniband of energy states periodically modulated with increasing magnetic field, exactly analogous to the behavior of a quantum ring spectrum.