Modelling & Simulation


Optimizing the electrocaloric effect by first-principles simulations: The role of strain and defects

Anna Grünebohm, Faculty of Physics, University of Duisburg-Essen and CENIDE, Duisburg, Germany
Madhura Marathe, Materials Theory, ETH Zürich, Zürich, Switzerland
Takeshi Nishimatsu, Institute for Materials Research (IMR), Tohoku University, Sendai, Japan
Claude Ederer, Materials Theory, ETH Zürich, Zürich, Switzerland

Ferroic cooling employing ferromagnetic (magnetocaloric effect) or ferroelectric (electrocaloric effect) materials is promising for novel sustainable cooling technologies [1]. In both cases, efficient cooling can be obtained in solid state devices.

However, commercial devices are still missing as many open questions have to be solved by an in the whole „Materials Chain“. For example, the operation temperature range is often restricted to small temperature intervals.

In this talk we focus on the modeling, simulation, and optimization of the electrocaloric effect. We have combined ab initio-based molecular dynamics simulations with a simple model for defects [2]. For polar defects, the temperature range of the large caloric response is broadened. Still more striking, a giant inverse caloric effect has been observed for the first time [2].

Additionally, epitaxial strain can be used to enhance the caloric response and shift the operation range [3,4]. In particular, tensile strain is promising to enhance the ECE of BaTiO3 around room temperature.

[1] X. Moya, et al., Nature Mater. 22,439 (2014)
[2] A. Grünebohm, et al., Phys. Rev. B (accepted)
[3] M. Marathe, et al., APL 104, 212902 (2014)
[4] A. Grünebohm, et al., APL 107, 102901 (2015).

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