Significant enhancement of resonance magnetoelectric coupling in miniaturized lead-free, NiFe2O4-BaTiO3 multilayers

With increasing demands toward device miniaturization, Pb-free magnetoelectric laminates (MELs) with a small lateral dimension of similar to 3 x 3 mm(2) have been synthesized by the tape-casting method. The MELs are composed of alternating layers of magnetostrictive NiFe2O4 and piezoelectric BaTiO3 with a uniform single layer thickness of t = 50 and 15 gm, respectively. Both laminates exhibit much larger longitudinal ME voltage coefficient alpha(E33) than the transverse ME voltage coefficient alpha(E31) at both off-resonant and resonant frequencies, which is attributed to the preferential easy-plane alignment of the magnetic moments. Furthermore, enhancement in alpha(E33) by more than 5 times has been achieved upon decreasing t from 50 to 15 mu m in both resonance and off-resonance conditions. The enhanced alpha(E33) values indicate that nearly ideal interface coupling between the ferromagnetic and piezoelectric layers is realized in the miniaturized, thinner MEL, pointing to practical application potential towards developing mass-produced, low-cost ME devices. (C) 2017 Elsevier B.V. All rights reserved.