Quantitative determination of anisotropic magnetoelectric coupling in BiFeO3–CoFe2O4 nanostructures

The transverse and longitudinal magnetoelectric susceptibilities (MES) were quantitatively determined for (001) heteroepitaxial BiFeO3–CoFe2O4 nanostructures. Both of these MES values were sharply enhanced at magnetic fields below 6 kOe and revealed asymmetric line shapes with respect to the dc magnetic field, demonstrating the strain-induced magnetoelectric effect. The maximum transverse MES, which reached as high as ∼60 mV/cm Oe, was about five times larger than the longitudinal MES. This observation signifies that transverse magnetostriction of the CoFe2O4 nanopillars is enhanced more than the bulk value due to preferred magnetic domain alignment along the [001] direction coming from compressive, heteroepitaxial strain.