Anomalous electrocaloric effect (ECE) with decreasing temperature upon application of an electric field is known to occur in antiferroelectrics (AFEs), and previous understanding refers to the field-induced canting of electric dipoles if there is no phase transitions. Here, we use a first-principle-based method to study the ECE in Nd-substituted BiFeO3 (BNFO) perovskite solid solutions, which has the Pnma-type AFE ground state. We demonstrate another scenario to achieve and explain anomalous ECE, emphasizing that explicit consideration of octahedral tiltings is indispensable for a correct understanding. This mechanism may be general for AFEs for which the antipolar mode is not the primary order parameter. We also find that the negative ECE can reach a large magnitude in BNFO.
@article{arxiv.2210.04138,
title = {Origin of negative electrocaloric effect in Pnma-type antiferroelectric perovskites},
author = {Ningbo Fan and Jorge Íñiguez and L. Bellaiche and Bin Xu},
journal= {arXiv preprint arXiv:2210.04138},
year = {2022}
}