A revisit to phonon-phonon scattering in single-layer graphene

TL;DR

This study investigates how four-phonon scatterings and temperature-dependent interatomic force constants influence thermal conductivity in graphene, revealing that four-phonon processes significantly reduce conductivity at room temperature.

Contribution

It introduces the importance of four-phonon scatterings and finite-temperature IFCs in accurately modeling phonon transport in graphene, extending previous three-phonon based analyses.

Findings

Four-phonon scatterings significantly reduce thermal conductivity.

Using IFCs at finite temperature yields more accurate predictions.

Phonon frequency broadening is essential for matching molecular dynamics results.

Abstract

Understanding the mechanisms of thermal conduction in graphene is a long-lasting research topic, due to its high thermal conductivity. Peierls-Boltzmann transport equation (PBTE) based studies have revealed many unique phonon transport properties in graphene, but most previous works only considered three-phonon scatterings and relied on interatomic force constants (IFCs) extracted at 0 K. In this paper, we explore the roles of four-phonon scatterings and the temperature dependent IFCs on phonon transport in graphene through our PBTE calculations. We demonstrate that the strength of four-phonon scatterings would be severely overestimated by using the IFCs extracted at 0 K compared with those corresponding to a finite temperature, and four-phonon scatterings are found to significantly reduce the thermal conductivity of graphene even at room temperature. In order to reproduce the prediction from molecular dynamics simulations, phonon frequency broadening has to be taken into account when determining the phonon scattering rates. Our study elucidates the phonon transport properties of graphene at finite temperatures, and could be extended to other crystalline materials.