Deconvolution of phonon scattering by ferroelectric domain walls and point defects in a PbTiO3 thin film deposited in a composition-spread geometry

TL;DR

This study analyzes how ferroelectric domain walls and point defects affect phonon scattering and thermal conductivity in a PbTiO3 thin film, revealing domain walls as the dominant scattering source across various compositions.

Contribution

It provides a quantitative deconvolution of phonon scattering sources in ferroelectric thin films, highlighting the dominant role of domain walls over point defects.

Findings

Ferroelectric domain walls are the main phonon scattering source.

Point defects have a lesser impact on thermal conductivity.

Reconfigurable domain walls can control thermal conductivity.

Abstract

We present a detailed analysis of the temperature dependence of the thermal conductivity of a ferroelectric PbTiO3 thin film deposited in a composition-spread geometry enabling a continuous range of compositions from ~25% titanium-deficient to ~20% titanium-rich to be studied. By fitting the experimental results to the Debye model we deconvolve and quantify the two main phonon scattering sources in the system: ferroelectric domain walls (DWs) and point defects. Our results prove that ferroelectric DWs are the main agent limiting the thermal conductivity in this system, not only in the stoichiometric region of the thin film ([Pb]/[Ti]~1), but also when the concentration of cation point defects is significant (up to ~15%). Hence, DWs in ferroelectric materials are a source of phonon scattering at least as effective as point defects. Our results demonstrate the viability and effectiveness of using reconfigurable DWs to control the thermal conductivity in solid-state devices.