Understanding the lattice thermal conductivity of SrTiO3 from an ab initio perspective

TL;DR

This study uses ab initio methods to analyze how structural distortions affect the lattice thermal conductivity of SrTiO3, revealing mechanisms involving acoustic modes and polar modes, with counterintuitive findings about octahedral rotations.

Contribution

It provides a detailed ab initio analysis of how structural distortions influence SrTiO3's thermal conductivity, highlighting two key mechanisms and a surprising effect of octahedral rotation angles.

Findings

Increasing octahedral rotation angle increases thermal conductivity.

Modification of acoustic mode dispersion affects thermal transport.

Polar modes play a significant role in thermal conductivity tuning.

Abstract

We present a detailed analysis of the structure dependence of the lattice thermal conductivity of SrTiO3. We have used both ab initio Molecular Dynamic simulations and Density Functional Theory calculations to decouple the effect of different structural distortions on the thermal conductivity. We have identified two main mechanisms for tuning the thermal conductivity when a distortion is applied. First, the modification of the acoustic-modes energy dispersion when a change in the lattice parameters is imposed and second, the low energy polar modes. In particular and counterintuitively, we have found that an increase in the angle of the oxygen octahedral rotations increases the thermal conductivity due to its coupling to these polar modes.