Light-induced valley currents and magnetization in graphene rings

TL;DR

This paper investigates how picosecond electromagnetic pulses induce ultrafast charge polarization, valley currents, and magnetization in a graphene ring, revealing light-controlled valleytronics effects.

Contribution

It introduces a novel mechanism for generating valley currents and magnetization in graphene rings using ultrafast light pulses, highlighting non-equilibrium valley population differences.

Findings

Ultrafast buildup of charge polarization and currents

Generation of non-equilibrium valley currents

Finite magnetization without charge current

Abstract

We study the non-equilibrium dynamics in a mesoscopic graphene ring excited by picoseconds shaped electromagnetic pulses. We predict an ultrafast buildup of charge polarization, currents and orbital magnetization. Applying the light pulses identified here, non-equilibrium valley currents are generated in a graphene ring threaded by a stationary magnetic flux. We predict a finite graphene ring magnetization even for a vanishing charge current; the magnetization emerges due to the light-induced difference of the valley populations.