Edge states and phase diagram for graphene under polarized light

TL;DR

This paper explores the topological phase transitions in graphene under circularly polarized light, revealing a rich phase diagram with multiple topological phases, high-Chern number behaviors, and the effects of resonances and disorder.

Contribution

It provides a comprehensive phase diagram for driven graphene, identifying up to ten topological phases and analyzing the effects of resonances and disorder on edge states.

Findings

High-Chern number behaviors are common in driven graphene.

One-photon resonance creates chiral edge states in the π-gap.

Two-photon resonance induces counter-propagating edge modes in the zero-energy gap.

Abstract

We investigate the topological phase transitions in graphene under the modulation of circularly polarized light, by analyzing the changes of edge states and its topological structures. A full phase diagram, with up to ten different topological phases, is presented in the parameter space spanned by the driving frequency and light strength. We find that the high-Chern number behavior is very common in the driven system. While the one-photon resonance can create the chiral edge states in the $\pi-$gap, the two-photon resonance will induce the counter-propagating edge modes in the zero-energy gap. When the driving light strength is strong, the number and even the chirality of the edge states may change in the $\pi-$gap. The robustness of the edge states to disorder potential are also examined. We close by discussing the feasibility of experimental proposals.