Materials design from non-equilibrium steady states: driven graphene as a tunable semiconductor with topological properties

TL;DR

This paper demonstrates how driving monolayer graphene with an optical phonon can create a tunable electronic gap and induce topological edge currents, enabling dynamic control of material properties.

Contribution

It introduces a theoretical method to engineer a tunable gap and topological features in graphene via non-equilibrium steady states driven by optical phonons.

Findings

A controllable electronic gap is generated in graphene by optical phonon excitation.

Steady states exhibit topological phenomena, including chiral edge currents.

Edge currents circulate fractional charge e/2 per cycle.

Abstract

Controlling the properties of materials by driving them out of equilibrium is an exciting prospect that has only recently begun to be explored. In this paper we give a striking theoretical example of such materials design: a tunable gap in monolayer graphene is generated by exciting a particular optical phonon. We show that the system reaches a steady state whose transport properties are the same as if the system had a static electronic gap, controllable by the driving amplitude. Moreover, the steady state displays topological phenomena: there are chiral edge currents, which circulate a fractional charge e/2 per rotation cycle, with frequency set by the optical phonon frequency.