Large Longitudinal Magnetoelectric Coupling in NiFe2O4–BaTiO3 Laminates

In contrast to the Pb-based magnetoelectric laminates (MELs), we find in the BaTiO3 and NiFe2O4 laminates (number of layers n=5–25) that the longitudinal magnetoelectric (ME) voltage coefficient αE33 becomes much larger than the transverse one due to preferential alignment of magnetic moments along the NiFe2O4 plane. Moreover, upon decreasing each layer thickness down to 15 µm, we realize enhanced αE33 up to 18 mV/(cmOe) and systematic increase of the ME sensitivity in proportion to n to achieve the largest in the Pb-free MELs (400×10-6 V/Oe), thereby providing pathways for tailoring ME coupling in mass-produced, environment friendly laminates.