Electrocaloric effects in multiferroics

An atomistic effective Hamiltonian is used to compute electrocaloric (EC) effects in rare-earth-substituted BiFeO3 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 magneto-electric coupling, and generates a peak of the EC response at the Neel temperature. These atomistic results and phenomenological model may be put in use to optimize EC coefficients.

Automated summary

An atomistic effective Hamiltonian is applied to calculate electrocaloric effects in rare-earth-substituted BiFeO3 multiferroics, followed by the development of a phenomenological model to interpret these calculations. The model suggests that the electrocaloric coefficient is determined by two terms involving electric quantities and the antiferromagnetic order parameter.