Nonperturbative quasiclassical theory of graphene photoconductivity

TL;DR

This paper develops a nonperturbative quasi-classical framework to analyze how low-frequency radiation affects the static conductivity of graphene, accounting for various external and material parameters, and compares it with perturbative approaches.

Contribution

It introduces a nonperturbative theory of graphene photoconductivity valid at strong fields and low frequencies, extending beyond third-order perturbation methods.

Findings

The theory accurately describes photoconductivity at frequencies up to twice the Fermi energy.

It identifies the limits of perturbative methods in strong-field regimes.

The results show how external field strength and material properties influence conductivity.

Abstract

We present a nonperturbative quasi-classical theory of graphene photoconductivity. We consider the influence of low-frequency (microwave, terahertz, mid-infrared) radiation on the static conductivity of a uniform graphene layer and calculate its photoconductivity as a function of frequency, polarization and strength of the external ac electric field, as well as on the material properties (electron density, scattering time) and temperature. The theory is valid at frequencies $\hbar\omega\lesssim 2E_F$ and at arbitrarily strong ac electric fields. We compare our results with those of the third-order perturbation theory and determine the applicability range of the perturbative solutions.