Phonon transport across twin boundaries and twin superlattices

TL;DR

This study uses atomistic simulations to explore how twin boundaries in superlattices of GaAs and InAs influence phonon transport, revealing regimes where interfaces act independently or as a collective metamaterial affecting thermal properties.

Contribution

It demonstrates the potential of crystal phase engineering to control phonon transport in superlattices without changing material composition.

Findings

Identification of two phonon transport regimes across twin boundaries.

Existence of a metamaterial-like behavior in segments with many interfaces.

Potential for thermal property tuning via interface density.

Abstract

Crystal phase engineering gives access to new types of superlattices where, rather than different materials, different crystal phases of the same material are juxtaposed. Here, by means of atomistic nonequilibrium molecular dynamics calculations, we study to what extent these periodic systems can be used to alter phonon transport, similarly to what has been predicted and observed in conventional superlattices based on heterointerfaces. We focus on twin superlattices in GaAs and InAs and highlight the existence of two different transport regimes: in one each interface behaves like an independent scatterer; in the other, a segment with a sufficiently large number of closely-spaced interfaces, is seen by propagating phonons as a metamaterial with its own thermal properties.