Converse magnetoelectric effect in CoFe₂O₄–BaTiO₃composites 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 αC≈(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.