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

Abstract

A detailed understanding of the 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 nonequilibrium 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 cutoff 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.

Thermal conductivity decomposition in two-dimensional materials: Application to graphene

“…The nonequilibrium heat current can be further decomposed for different frequencies, as recently demonstrated by Sääskilahti et al [31,32]. Here, we extend their method to include the in-out decomposition.…”

“…We note that Sääskilahti et al [32] and Gill-Comeau and Lewis [34] have also demonstrated that applying the harmonic approximation in the calculation of the microscopic heat current barely affects the results. This is due to the small anharmonicity of the graphene lattice but cannot be guaranteed for other cases [31].…”

“…In Sec. II C, the spectral decomposition method of Sääskilahti et al [31,32] is generalized to include the in-out decomposition. Some details of our MD simulations are then presented in Sec.…”

“…However, when used in their traditional form, little insight can be gained regarding the underlying transport * brucenju@gmail.com mechanisms. There have been intensive efforts in developing MD-based methods for studying spectrally decomposed properties [25][26][27][28][29][30][31][32][33][34][35], but most of them are targeted for general materials. One exception is the method by Gill-Comeau and Lewis [34], where the total thermal conductivity is decomposed into a single-particle component and a collective one, the latter being crucial to materials in which the nonresistive normal (non-umklapp) scattering is important, which is the case for graphene [10,14,15].…”

Phonon transmission across an interface between two crystals

“…The role of anharmonicity of oscillations in the phonon transmission across the interface is considered in the paper [15]. In the most recent study [16], it has been found that atoms at the interface oscillate with a frequency exceeding the maximum possible frequency in a given crystal.…”