Minimum and maximum conductance of a thin film layer bridged interface: the role of anharmonicity and layer thickness

TL;DR

This paper investigates how anharmonicity and layer thickness influence the thermal conductance of thin film interfaces with an intermediate layer, revealing conditions under which conductance is enhanced or reduced.

Contribution

It introduces a detailed analysis of anharmonic effects on interfacial phonon transport and identifies how temperature and layer thickness tune conductance.

Findings

Anharmonicity can significantly increase conductance via inelastic phonon channels.

The additive resistance rule holds for thin bridge layers but fails at larger thicknesses.

Conductance can be optimized by adjusting temperature and layer thickness.

Abstract

We study the role of anharmonicity at interfaces with an added intermediate layer designed to facilitate interfacial phonon transport. Our results demonstrate that while in the harmonic limit the bridge may lower the conductance due to fewer available channels, anharmonicity can strongly enhance the thermal conductance of the bridged structure due to added inelastic channels. Moreover, we show that the effect of anharmonicity on the conductance can be tuned by varying temperature or the bridge layer thickness, as both parameters change the total rate of occurrence of phonon-phonon scattering processes. Additionally, we show that the additive rule of thermal resistances(Ohms law) is valid for bridge layer thickness quite shorter than the average bulk MFP, beyond the regime it would be expected to fail.