Unconventional optical response in monolayer graphene upon dominant intraband scattering

TL;DR

This paper reveals unconventional optical responses in doped monolayer graphene caused by dominant intraband scattering, deviating from universal conductivity, with analytical models aligning with Kubo calculations.

Contribution

It introduces a semi-classical multiband Boltzmann framework to analyze intraband scattering effects on graphene's optical conductivity, highlighting novel low-doping phenomena.

Findings

Unconventional linear optical response deviates from universal conductivity

Dominant intraband scattering causes significant deviations at low doping

High temperature or overdoping restores Drude-like behavior

Abstract

Scattering dynamics influence the graphenes transport properties and inhibits the charge carrier deterministic behaviour. The intra or inter-band scattering mechanisms are vital for graphenes optical conductivity response under specific considerations of doping. Here, we investigated the influence of scattering systematically on optical conductivity using a semi-classical multiband Boltzmann equation with inclusion of both electron-electron $\&$ electron-phonon collisions. We found unconventional characteristics of linear optical response with a significant deviation from the universal conductivity $\frac{e^2}{4\hbar}$ in doped monolayer graphene. This is explained through phenomenological relaxation rates under low doping regime with dominant intraband scattering. Such novel optical responses are vanished at high temperatures or overdoping conditions due to strong Drude behaviour. With the aid of approximations around Dirac points we have developed analytical formalism for many body interactions and is in good agreement with the Kubo approaches.