Ballistic Thermal Conduction across Acoustically Mismatched Solid Junctions

TL;DR

This paper develops an atomistic approach to calculate ballistic thermal conduction across acoustically mismatched solid junctions, revealing mode-dependent transmission and resonant conductance effects in nanotubes and superlattices.

Contribution

It introduces a lattice dynamic method to compute phonon transmission and thermal conductance in nanostructure junctions, providing new insights into mode dependence and resonant phenomena.

Findings

Mode-dependent phonon transmission in nanotube junctions

Resonant modulation of thermal conductance in superlattices

New interpretation of experimental thermal conductance data

Abstract

We derive expressions for energy flow in terms of lattice normal mode coordinates and energy transmission involving reduced group velocities. With a version of Landauer formula appropriate for lattice dynamic approach, the phonon transmission coefficients and thermal conductance are calculated for two kinds of acoustically mismatched junctions: different chirality nanotubes (11,0) to (8,0), and Si-Ge superlattice structure. Our calculation shows a mode-dependent transmission in nanotube junction and a resonantly modulated ballistic thermal conductance in superlattice. The superlattice result suggests a new interpretation of the experimental data. Our approach provides an atomistic way for the calculation of thermal conduction in nanostructure.