Magnetoelectric effects in bilayers and multilayers of magnetostrictive and piezoelectric perovskite oxides

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 ${\ensuremath{\alpha}}_{E}$ 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 ${\ensuremath{\alpha}}_{E}$ 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 ${\ensuremath{\alpha}}_{E}$ shows hysteresis and remanence. A general increase in ${\ensuremath{\alpha}}_{E}$ is observed with increasing frequency or decreasing temperature. There is good qualitative agreement between theory and data for the magnetic-field dependence of ${\ensuremath{\alpha}}_{E}.$