Converse magnetoelectric effect inCoFe2O4–BaTiO3 composites with a core–shell structure

Abstract

Multiferroic composites were prepared by coveringCoFe2O4 nanoparticleswith a shell of BaTiO3 using a sol–gel technique. Scanning probe microscopy confirmed the formation of acore–shell structure with a magnetic core and a piezoelectric shell. The conversemagnetoelectric effect was studied at different temperatures and bias fields. Themagnetoelectric coefficient peaks at approximately 270 K and reaches the valueαC≈(2.2 ± 0.1)10 − 11 s m − 1, which surpasses those reported previously for similar structures. A change of the sign ofthe magnetoelectric coefficient observed for an increasing magnetic bias field is relatedto the non-monotonic field dependence of magnetostriction in polycrystallineCoFe2O4.