Surprisingly high magneto-electric coupling in cubic Co0.7Fe2.3O4-SrTiO3 nano-composites

Magnetoelectric (ME) coupling of (x)SrTiO3-(1-x)Co0.7Fe2.3O4 synthesized by the sol-gel method is presented in this study. The presence of constituent phases of Co0.7Fe2.3O4 (CFO) and SrTiO3(STO), and their strain mechanism in the composites were studied by x-ray diffraction. The field emission scanning electron micrographs confirmed well-distributed CFO and STO phases in the composites. The dielectric constant (ε′) and loss tangent (tanδ) of the composites were studied as a function of frequency. CFO and all the composites exhibit typical ferromagnetic hysteresis loops whereas their ferroelectric hysteresis loops show leaky behavior. CFO and STO lattices experiences compressive and tensile strain respectively that further promoting magnetostriction and electrostrictions in CFO and STO respectively. Strain mediated high magnetoelectric coefficient, αME = 9.1 mV/cm Oe is obtained for the composite having 50% STO and 50% CFO content. These results demonstrate that the lead free STO-CFO could be effective as magnetoelectric composite and may provide an alternative option over toxic lead contain materials for environmentally friendly ME device application.