Phonon Scattering in the Complex Strain Field of a Dislocation

TL;DR

This paper investigates how inhomogeneous strain fields around dislocations affect phonon scattering and thermal conductivity in PbTe, using molecular dynamics simulations and a flux method to analyze frequency-dependent scattering.

Contribution

It introduces a detailed analysis of phonon scattering in complex, inhomogeneous strain fields caused by dislocations, advancing understanding of strain-phonon interactions.

Findings

Dislocations create spatially varying strain fields affecting phonon scattering.

Frequency-dependent phonon scattering rates are influenced by local strain variations.

Results provide guidance for thermal management through structural design.

Abstract

Strain engineering is critical to the performance enhancement of electronic and thermoelectric devices because of its influence on the material thermal conductivity. However, current experiments cannot probe the detailed physics of the phonon-strain interaction due to the complex, inhomogeneous, and long-distance features of the strain field in real materials. Dislocations provide us with an excellent model to investigate these inhomogeneous strain fields. In this study, non-equilibrium molecular dynamics simulations were used to study the lattice thermal conductivity of PbTe under different strain status tuned by dislocation densities. The extended 1D McKelvey-Shockley flux method was used to analyze the frequency dependence of phonon scattering in the inhomogeneously strained regions of dislocations. A spatially resolved phonon dislocation scattering process was shown, where the unequal strain in different regions affected the magnitude and frequency-dependence of the scattering rate. Our study not only advances the knowledge of strain scattering of phonon propagation but offers fundamental guidance on optimizing thermal management by structure design.