Impurity States and Indirect Exchange Interaction in Irradiated Graphene

TL;DR

This paper theoretically explores how off-resonant circularly polarized light influences impurity states and exchange interactions between magnetic impurities in graphene, revealing tunable magnetic properties via irradiation.

Contribution

It introduces a non-perturbative analysis of impurity levels and exchange interactions in irradiated graphene, highlighting the tunability of magnetic interactions with light.

Findings

Impurity levels appear inside a dynamical band gap created by irradiation.

Exchange interaction range is extended and shows resonance features.

Magnetic exchange energy can be extensively tuned by light irradiation.

Abstract

We theoretically investigate the impurity levels and exchange interaction between magnetic impurities in graphene driven by an off-resonant circularly polarized light field. Our analysis captures the non-perturbative effects resulting from scattering with magnetic impurities with a strong onsite potential. Under irradiation, a dynamical band gap opens up at the Dirac point, allowing impurity levels to exist inside the gap. These impurity levels are shown to give rise to a resonance feature in the exchange energy for impurities located either at the same or different sublattices. The exchange interaction also shows a wider spatial range of antiferromagnetic behavior due to irradiation. Our work demonstrates that the exchange energy of magnetic impurities in graphene is extensively tunable by light irradiation in the presence of strong potential scattering.