Magnetoelectric bilayer and multilayer structures of magnetostrictive and piezoelectric oxides

Materials capable of field conversion, from magnetic to electric or vice versa, are of fundamental and technological importance. We report a giant magnetoelectric (ME) effect that results from stress-mediated electromagnetic coupling in bilayers and multilayers of nickel ferrite and lead zirconate titanate. Samples with layer thickness 10-200 mum were synthesized by doctor-blade techniques. The magnetoelectric voltage coefficient alpha (E) ranges from 460 mV/cm Oe in bilayers to 1500 mV/cm Oe for multilayers. The transverse effect is an order of magnitude stronger than longitudinal alpha (E). The ME coefficient is maximum at room temperature and a general increase in alpha (E) is observed with increasing frequency. Data on the dependence Of alpha (E) on volume fraction of the two phases and bias magnetic field are in excellent agreement with a theoretical model for a perfectly bonded bilayer.