Ballistic Phonon Thermal Transport in Multi-Walled Carbon Nanotubes

TL;DR

This study demonstrates that multi-walled carbon nanotubes can conduct heat ballistically at the quantum limit, with experimental validation of the thermal conductance quantum and insights into breakdown mechanisms.

Contribution

First experimental measurement of ballistic phonon thermal conductance in multi-walled carbon nanotubes, confirming quantum limits and proposing a self-heating technique for device improvement.

Findings

Nanotubes exhibit ballistic phonon thermal transport reaching quantum limits.

Thermal conductance quantum matches theoretical predictions.

Self-heating technique significantly enhances nanotube device conductance.

Abstract

We report electrical transport experiments using the phenomenon of electrical breakdown to perform thermometry that probe the thermal properties of individual multi-walled nanotubes. Our results show that nanotubes can readily conduct heat by ballistic phonon propagation, reaching a quantum-mechanical limit to thermal conductance. We determine the thermal conductance quantum, the ultimate limit to thermal conductance for a single phonon channel, and find good agreement with theoretical calculations. Moreover, our results suggest a breakdown mechanism of thermally activated C-C bond breaking coupled with the electrical stress of carrying ~10^12 A/m^2. We also demonstrate a current-driven self-heating technique to improve the conductance of nanotube devices dramatically.