Reduced Thermal Conductivity of Nanowires and Nanoribbons with Dynamically Rough Surfaces and the "Problem of One-Dimensional Heat Conductors"

TL;DR

This paper combines analytical modeling and molecular dynamics simulations to show that dynamically rough surfaces in nanowires and nanoribbons lead to finite, length-independent thermal conductivity, contrasting with divergent behavior in smooth-surface systems.

Contribution

It introduces a model explaining how surface roughness causes momentum-nonconserving phonon scattering, reducing thermal conductivity in quasi-one-dimensional nanostructures.

Findings

Finite, length-independent thermal conductivity predicted and confirmed.

Rough surfaces induce momentum-nonconserving phonon scattering.

Contrasts with anomalous heat conduction in smooth-surface nanowires.

Abstract

We present analytical model and molecular dynamics simulations of phonon heat transport in nanowires and nanoribbons with anharmonic lattices and dynamically rough surfaces and edges. In agreement with recent experiments on heat transport in single-crystalline silicon nanowires with rough surfaces, our model and simulations predict finite and length-independent phonon thermal conductivity in such quasi-one-dimensional systems, in contrast to anomalous phonon thermal conductivity of corresponding momentum-conserving systems with atomically smooth surfaces, divergent with the system length. Within our model, the main cause of thermal conductivity reduction is momentum-nonconserving scattering of longitudinal acoustic phonons by anharmonic side phonon leads in quasi-one-dimensional phonon waveguide with dynamically rough surface or edge layers.