Electrocaloric effects in ferroelectrics and multiferroics from first principles

The electrocaloric (EC) effect characterizes the change in temperature or entropy of a material under the application of an external electric field . Ferroelectric and multiferroic materials have attracted considerable interest due to their potential for efficient solid-state refrigeration in a broad range of applications. In this review, we present recent applications of first-principles-based effective Hamiltonian , second-principles method, and spin Heisenberg model to study the EC effect in ferroelectrics, relaxor ferroelectrics , and multiferroic materials . Specifically, these methods are used to investigate the EC effect in perovskite ferroelectrics Pb(Zr 0.4 Ti 0.6 )O 3 , (Ba 0.5 Sr 0.5 )TiO 3 , PbTiO 3 , BaTiO 3 and PbTiO 3 /SrTiO 3 superlattices , relaxor ferroelectrics Ba(Zr, Ti)O 3 and Pb(Mg, Nb)O 3 , as well as rare-earth-substituted BiFeO 3 , BiCoO 3 and BiFeO 3 multiferroics, and Nd-substituted BiFeO 3 antiferroelectric solid solutions . Large electrocaloric responses are predicted in some of these compounds. In addition, we review the phenomenological models that can be used to analyze and understand these EC effect results.