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MM: Fachverband Metall- und Materialphysik

MM 29: Topical session: Caloric effects in ferroic materials III - Electrocalorics

MM 29.1: Talk

Wednesday, March 9, 2016, 10:15–10:30, H39

Abnormal electrocaloric effect studied by lattice based Monte-Carlo simulations — •Kai-Christian Meyer, Constanze Kalcher, Alexander Stukowski, and Karsten Albe — TU Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt

The abnormal electrocaloric effect (ECE) was first found by Peräntie et al. in 2010 in PMN-PT single crystals. [1] Contrary to the normal ECE, an increase of the electric field leads in these materials to a decrease of the temperature. In this work we show that the abnormal ECE can be described within a lattice based random bond model that only includes next neighbor interactions and an external electric field. The negative temperature change can be observed when the electric field lowers the order (configurational entropy) of the polarization vectors. This is the case when the system is in a antiferroelectric state or polar defects with polarization antiparallel to the external field are present. These findings are in agreement with a more elaborate model which includes long-range dipole-dipole interaction and gradient terms. [2]

[1] J. Peräntie, et al., Phys. Rev. B 82, 134119 (2010)

[2] Y. Ma, et al., arXiv:1507.05004