Role of anharmonic phonon scattering in the spectrally decomposed thermal conductance at planar interfaces

TL;DR

This study reveals how anharmonic phonon scattering influences spectral heat transfer at interfaces between mismatched solids, highlighting inelastic effects that enhance thermal conductance at high temperatures.

Contribution

It introduces a spectral decomposition method based on molecular dynamics to analyze anharmonic effects on interfacial heat transfer, emphasizing inelastic phonon processes.

Findings

Anharmonic interactions significantly enhance heat transfer at high frequencies.

Inelastic effects facilitate energy dissipation of evanescent modes.

Frequency-doubling and halving processes are key in phonon energy transfer.

Abstract

Detailed understanding of vibrational heat transfer mechanisms between solids is essential for the efficient thermal engineering and control of nanomaterials. We investigate the frequency dependence of anharmonic scattering and interfacial thermal conduction between two acoustically mismatched solids in planar contact by calculating the spectral decomposition of the heat current flowing through an interface between two materials. The calculations are based on analyzing the correlations of atomic vibrations using the data extracted from non-equilibrium molecular dynamics simulations. Inelastic effects arising from anharmonic interactions are shown to significantly facilitate heat transfer between two mass-mismatched face-centered cubic lattices even at frequencies exceeding the cut-off frequency of the heavier material due to (i) enhanced dissipation of evanescent vibrational modes and (ii) frequency-doubling and frequency-halving three-phonon energy transfer processes at the interface. The results provide substantial insight into interfacial energy transfer mechanisms especially at high temperatures, where inelastic effects become important and other computational methods are ineffective.