Length-dependent thermal conductivity in suspended single-layer graphene

TL;DR

This study investigates how the thermal conductivity of suspended single-layer graphene varies with temperature and length, revealing a unique logarithmic divergence due to its two-dimensional phonon transport properties.

Contribution

It provides experimental and simulation evidence that graphene's thermal conductivity increases logarithmically with length at room temperature, unlike bulk materials.

Findings

Thermal conductivity in graphene increases with sample length.

Conductivity remains logarithmically divergent even for large samples.

Results highlight the role of two-dimensional phonon behavior in thermal transport.

Abstract

Graphene exhibits extraordinary electronic and mechanical properties, and extremely high thermal conductivity. Being a very stable atomically thick membrane that can be suspended between two leads, graphene provides a perfect test platform for studying thermal conductivity in two-dimensional systems, which is of primary importance for phonon transport in low-dimensional materials. Here we report experimental measurements and non-equilibrium molecular dynamics simulations of thermal conduction in suspended single layer graphene as a function of both temperature and sample length. Interestingly and in contrast to bulk materials, when temperature at 300K, thermal conductivity keeps increasing and remains logarithmic divergence with sample length even for sample lengths much larger than the average phonon mean free path. This result is a consequence of the two-dimensional nature of phonons in graphene and provides fundamental understanding into thermal transport in two-dimensional materials.