Tuning the caloric response of BaTiO$_3$ by tensile epitaxial strain

TL;DR

This study uses ab initio molecular dynamics to show how tensile epitaxial strain can tune the electrocaloric effect in BaTiO$_3$, enabling temperature range optimization for ferroic cooling applications.

Contribution

It demonstrates that tensile strain can shift the electrocaloric operation temperature range and induce domain state transformations, enhancing the material's cooling performance.

Findings

Strain shifts operation temperature by hundreds of Kelvin.

In-plane electric field induces domain transformations and additional caloric peaks.

Caloric response scales linearly with field over a broad temperature range.

Abstract

We investigate the effect of epitaxial strain on the electrocaloric effect (ECE) in BaTiO$_3$ by means of ab initio based molecular dynamics simulations. We show that tensile strain can be used to optimize the operation range for ferroic cooling. Strain in the range of $\leq 1$ % can be used to shift the operation temperature by several hundreds of Kelvin both to higher and lower temperatures, depending on the direction of the external field. In addition, the transformation between multi-domain and mono-domain states, induced by an in-plane electric field, results in an additional peak of the adiabatic temperature change at lower temperatures, and a broad temperature interval where the caloric response scales linearly with the applied field strength, even up to very high fields.