Electrocaloric effects in multiferroics

Abstract

An atomistic effective Hamiltonian is used to compute electrocaloric (EC) effects in rare-earth substituted BiFeO${}_3$ multiferroics. A phenomenological model is then developed to interpret these computations, with this model indicating that the EC coefficient is the sum of two terms, that involve electric quantities (polarization, dielectric response), the antiferromagnetic order parameter, and the coupling between polarization and antiferromagnetic order. The first one depends on the polarization and dielectric susceptibility, has the analytical form previously demonstrated for ferroelectrics, and is thus enhanced at the ferroelectric Curie temperature. The second one explicitly involves the dielectric response, the magnetic order parameter and a specific magnetoelectric coupling, and generates a peak of the EC response at the Néel temperature. These atomistic results and phenomenological model may be put in use to optimize EC coefficients.

6 pages, 3 figures

References in corpus (5)

• Electric-field-induced spin-flop in BiFeO3 single crystals at room-temperature
• Phase diagram of Pb(Zr,Ti)O3 solid solutions from first principles
• Giant electrocaloric effect around T${}_c$
• Electrocaloric effects in the lead-free Ba(Zr,Ti)O${}_3$ relaxor ferroelectric from atomistic simulations
• Giant Direct and Inverse Electrocaloric Effects in Multiferroic Thin Films