Magnetoelectric effect in composites of piezoelectric and piezomagnetic phases

The magnetoelectric effect in composites of piezoelectric and piezomagnetic phases is investigated theoretically. The magnetoelectric effect is totally absent in these two constituent phases, and so it is a new property of the composites. A generalized theoretical framework based on a Green’s function method and perturbation theory is proposed to treat the coupled magnetoelectric behavior in the composites. Explicit relations for determining the effective magnetoelectric effect in the composites are derived, and the different approximate expressions for the magnetoelectric coefficient of the fibrous composites with 1-3 or 3-1 connectivity of phases are given. To illustrate the technique, numerical calculations of the magnetoelectric coefficients of the ${\mathrm{BaTiO}}_3$-${\mathrm{CoFe}}_2$${\mathrm{O}}_4$ composites for various phase compositions and particle shapes are performed. The theoretical estimates are shown to be in agreement with available experimental results, and also show the interesting magnetoelectric behavior of the composites.