The ferroelectric domain wall phonon polarizer

TL;DR

This paper demonstrates through atomistic simulations that ferroelectric domain walls can act as phonon polarizers, selectively filtering transverse phonons while allowing longitudinal phonons to pass, thus enabling control over heat flux at the nanoscale.

Contribution

It introduces the concept of using ferroelectric domain walls as phonon polarizers, a novel approach for controlling heat flux in materials.

Findings

Domain walls suppress transverse phonons significantly.

Longitudinal phonons can traverse multiple domain walls with minimal scattering.

Structural inhomogeneity enables selective phonon polarization control.

Abstract

Modulating the polarization of a beam of quantum particles is a powerful method to tailor the macroscopic properties of the ensuing energy flux as it directly influences the way in which its quantum constituents interact with other particles, waves or continuum media. Practical polarizers, being well developed for electric and electromagnetic energy, have not been proposed to date for heat fluxes carried by phonons. Here we report on atomistic phonon transport calculations demonstrating that ferroelectric domain walls can operate as phonon polarizers when a heat flux pierces them. Our simulations for representative ferroelectric perovskite PbTiO$_3$ show that the structural inhomogeneity associated to the domain walls strongly suppresses transverse phonons, while longitudinally polarized modes can travel through multiple walls in series largely ignoring their presence.