Polarization and plasmons in hot photoexcited graphene

TL;DR

This paper introduces an exact method to calculate polarization and plasmon properties in hot, photoexcited graphene with non-equilibrium carriers, revealing behaviors different from equilibrium and aiding understanding of carrier interactions.

Contribution

It provides a novel, exact approach for computing polarization functions in non-equilibrium graphene, applicable to various carrier distributions including hot carriers after photoexcitation.

Findings

Different behavior from equilibrium in polarization functions

Method applicable to arbitrary isotropic distributions

Highlights importance for understanding carrier interactions

Abstract

We present a robust and exact method for calculating the polarization function and plasmon dispersion of graphene, for an arbitrary (isotropic) non-equilibrium carrier distribution, within random phase approximation (RPA). This is demonstrated for a range of carrier distributions, including hot carrier distributions which occur within the femtoseconds following photoexcitation. We show that qualitatively different behaviour from the equilibrium case can occur. As the polarization function determines dynamic screening, its calculation shall be essential to quantifying carrier-carrier scattering channels for graphene far from equilibrium.