Converse magnetoelectric effect in CoFe2O4–BaTiO3composites with a core–shell structure

Multiferroic composites were prepared by covering CoFe 2 O 4 nanoparticles with a shell of BaTiO 3 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 α C ≈(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 CoFe 2 O 4 .