Phonon Coherent Resonance and Its Effect on Thermal Transport In Core-Shell Nanowires

TL;DR

This study investigates how phonon coherent resonance affects thermal transport in core-shell nanowires, revealing that phonon mode resonance can localize modes and reduce thermal conductivity, offering a new way to tune heat flow.

Contribution

It demonstrates the presence of phonon coherent resonance in core-shell nanowires and links it to reduced thermal conductivity, a novel insight into nanoscale heat transport.

Findings

Oscillation in heat current autocorrelation observed only in core-shell nanowires.

Phonon resonance causes localization of longitudinal modes.

Thermal conductivity is reduced due to phonon mode localization.

Abstract

We study heat current autocorrelation function and thermal conductivity in core-shell nanowires by using molecular dynamics simulations. Interestingly, a remarkable oscillation effect in heat current autocorrelation function is observed in core-shell NWs, while the same effect is absent in pure silicon nanowires, nanotube structures and random doped nanowires. Detailed characterizations of the oscillation signal reveal that this intriguing oscillation is caused by the coherent resonance effect of the transverse and longitudinal phonon modes. This phonon resonance results in the localization of the longitudinal modes, which leads to the reduction of thermal conductivity in core-shell nanowires. Our study reveals that a coherent mechanism can be used to tune thermal conductivity in core-shell nanowires.