Converse magnetoelectric effect in CoFe2O4-BaTiO3 composites with a core-shell structure

Multiferroic composites were prepared by covering CoFe2O4 nanoparticles with a shell of BaTiO3 using a sol-gel technique. Scanning probe microscopy confirmed the formation of a core-shell structure with a magnetic core and a piezoelectric shell. The converse magnetoelectric effect was studied at different temperatures and bias fields. The magnetoelectric coefficient peaks at approximately 270 K and reaches the value alpha(C) approximate to (2.2 +/- 0.1) 10(-11) s m(-1), which surpasses those reported previously for similar structures. A change of the sign of the magnetoelectric coefficient observed for an increasing magnetic bias field is related to the non-monotonic field dependence of magnetostriction in polycrystalline CoFe2O4.