Intense-pulse dynamics of massless Dirac electrons

TL;DR

This paper explores how intense short light pulses interact with massless Dirac electrons in 2D materials, revealing unique excitation behaviors and enabling high valley polarization in graphene.

Contribution

It demonstrates the coupling dynamics of short light pulses with Dirac fermions and achieves over 70% valley polarization using simple pulse shapes.

Findings

Unusual scaling of excitation dynamics with light wavelength.

Efficient coupling near Dirac points due to linear dispersion.

Achieved >70% valley polarization in graphene.

Abstract

We identify and describe how intense short light pulses couple to massless Dirac fermions in two-dimensional systems. The ensuing excitation dynamics exhibits unusual scaling with the wavelength of the light due the linear dispersion of the band structure and the fact that light coupling is efficient only close to the Dirac points. We exploit these features to achieve valley polarization of more than 70 % with simple pulse shapes. Quantitative results are given for pristine graphene.