The observation of strong magnetoelectric effects is reported in layered composites of ferromagnetic lanthanum manganites and piezoelectric lead zirconate titanate (PZT). Studies were made on thick-film structures of ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_3$ (LSMO)-PZT and ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_3$ (LCMO)-PZT. The low-frequency magnetoelectric (ME) voltage coefficient ${\alpha }_E$ was measured in bilayers and multilayers synthesized by tape casting. The effect is stronger in LSMO-PZT than in LCMO-PZT, and is weaker in multilayers compared to bilayers. A maximum ${\alpha }_E$ of 60 mV/cm Oe is measured for the transverse ME effect and is a factor of 2 to 3 higher than the longitudinal effect. The bias magnetic-field dependence of ${\alpha }_E$ shows hysteresis and remanence. A general increase in ${\alpha }_E$ is observed with increasing frequency or decreasing temperature. There is good qualitative agreement between theory and data for the magnetic-field dependence of ${\alpha }_E.$

• Received 3 July 2001

DOI:https://doi.org/10.1103/PhysRevB.65.134402