Nonlinear thermal transport and negative differential thermal conductance in graphene nanoribbons

TL;DR

This study uses molecular dynamics to explore nonlinear thermal transport in graphene nanoribbons, revealing tunable negative differential thermal conductance that depends on bias application and ribbon geometry, with implications for nanoscale thermal management.

Contribution

It demonstrates the occurrence and control of negative differential thermal conductance in graphene nanoribbons under large temperature biases, including effects of geometry and bias application methods.

Findings

NDTC occurs beyond linear response regime in GNRs.

NDTC can be tuned or eliminated by changing bias application or length.

NDTC exists only when heat flows from narrower to wider ends in triangular GNRs.

Abstract

We employ classical molecular dynamics to study the nonlinear thermal transport in graphene nanoribbons (GNRs). For GNRs under large temperature biases beyond linear response regime, we have observed the onset of negative differential thermal conductance (NDTC). NDTC is tunable by varying the manner of applying the temperature biases. NDTC is reduced and eventually disappears when the length of the GNR increases. We have also observed NDTC in triangular GNRs, where NDTC exists only when the heat current is from the narrower to the wider end. These effects may be useful in nanoscale thermal managements and thermal signal processing utilizing GNRs.