Isotopic effects on the thermal conductivity of graphene nanoribbons: localization mechanism

TL;DR

This study investigates how isotopic doping affects the thermal conductivity of graphene nanoribbons, revealing that doping reduces conductivity initially but the effect diminishes at higher doping levels, with temperature dependence also altered.

Contribution

It provides new insights into the localization mechanism of phonons in doped graphene nanoribbons through molecular dynamics simulations with quantum correction.

Findings

Isotopic doping reduces thermal conductivity in low doping regions.

Thermal conductivity increases with temperature, more slowly in doped GNR.

Localized phonon modes increase with doping, affecting thermal transport.

Abstract

Thermal conductivity of graphene nanoribbons (GNR) with length 106~{\AA} and width 4.92~{\AA} after isotopic doping is investigated by molecular dynamics with quantum correction. Two interesting phenomena are found: (1) isotopic doping reduces thermal conductivity effectively in low doping region, and the reduction slows down in high doping region; (2) thermal conductivity increases with increasing temperature in both pure and doped GNR; but the increasing behavior is much more slowly in the doped GNR than that in pure ones. Further studies reveal that the physics of these two phenomena is related to the localized phonon modes, whose number increases quickly (slowly) with increasing isotopic doping in low (high) isotopic doping region.