Flexocaloric Response Of Epitaxial Ferroelectric Films

The flexoelectric effect in dielectric materials generates an electric polarization as a result of strain gradient. Here, we show that the flexoelectric response also produces a flexocaloric adiabatic temperature variation in heteroepitaxial ferroelectric films that are either partially or completely relaxed. The flexocaloric temperature change of (001) BaTiO3 films on (001) SrTiO3 substrates is computed as a function of film thickness and temperature. Our calculations predict that a built-in flexocaloric temperature change of 0.61 degrees C can be realized in 20 nm thick epitaxial BaTiO3 films when compared with the intrinsic electrocaloric response of 0.75 degrees C for bulk, single-crystal BaTiO3 at 25 degrees C and applied electric field of 200 kV/cm. This demonstrates that the flexocaloric response can supplement electrocaloric temperature changes in thin film ferroelectrics and may play an important role in potential applications in on-chip solid-state cooling. Published by AIP Publishing.