Tuning Coherent-Phonon Heat Transport in LaCoO$_3$/SrTiO$_3$ Superlattices

TL;DR

This study demonstrates that coherent phonons significantly influence thermal conductivity in LaCoO3/SrTiO3 superlattices and can be tuned via superlattice periodicity, offering new control methods for thermal management in nanostructures.

Contribution

It reveals the substantial role of coherent phonons in oxide superlattices and introduces a tuning strategy based on superlattice periodicity without altering overall thickness.

Findings

Coherent phonons contribute significantly to thermal conductivity up to room temperature.

Thermal conductivity can be tuned by 20% through small changes in superlattice periodicity.

Interface mixing and epitaxial relaxation are key factors affecting thermal transport.

Abstract

Accessing the regime of coherent phonon propagation in nanostructures opens enormous possibilities to control the thermal conductivity in energy harvesting devices, phononic circuits, etc. In this paper we show that coherent phonons contribute substantially to the thermal conductivity of LaCoO3/SrTiO3 oxide superlattices, up to room temperature. We show that their contribution can be tuned through small variations of the superlattice periodicity, without changing the total superlattice thickness. Using this strategy, we tuned the thermal conductivity by 20% at room temperature. We also discuss the role of interface mixing and epitaxial relaxation as an extrinsic, material dependent key parameter for understanding the thermal conductivity of oxide superlattices.