  Magnetoelectric (ME) coupling at low frequencies and at x-band have been
investigated in layered samples containing zinc substituted lithium ferrite and
lead zirconate titanate (PZT). Multilayers of Li0.5-x/2ZnxFe2.5-x/2O4 (LZFO)
(x=0-0.4) and PZT were prepared by lamination and sintering of thick films. At
low frequencies (10-1000 Hz), the ME voltage coefficient for transverse fields
is higher than for longitudinal fields. With Zn substitution in the ferrite,
transverse coupling increases to a maximum for x=0.3 and then decreases for
higher x. Analysis based on our model for a bilayer implies an efficient
magneto-mechanical coupling with Zn substitution, resulting in strong ME
interactions. Microwave ME coupling is studied through measurements of shift in
the ferromagnetic resonance field due to an applied electric field. Estimated
ME constants from such data are in agreement with our model for a ferrite-PZT
bilayer.
