LAUSR

Abstract Magnetoelectric composites provide large enough room-temperature functional responses to enable a range of novel technologies, like uncooled high-sensitivity magnetic sensors. Magnetoelectricity in these composites appears as a product property of the piezoresponses of two elastically coupled ferroic phases. Coefficients then depend not only on the magnetostriction and piezoelectricity of the components, but also on interface quality. Different composite approaches are under development, among which cofired ceramic layered structures of ferrimagnetic spinel and ferroelectric perovskite oxides stand out because direct bonding between phases is attained, which facilitates miniaturization. An aspect rarely investigated is the role of the electrical characteristics of the magnetostrictive material beyond their effect on ferroelectric poling. We report here a three-fold enhancement of magnetoelectric coefficients by the only adjustment of the grain boundary conductivity of the spinel oxide. Significant differences in poling level are ruled out, and the effect is related with changes in the composite effective permittivity.