  Low frequency magnetoelectric (ME) coupling has been investigated in bulk and
multilayers of cobalt zinc ferrite, Co1-xZnxFe2O4 (x=0-0.6), and lead zirconate
titanate. In bulk samples, the transverse and longitudinal couplings are weak
and are of equal magnitude. A substantial strengthening of ME interactions is
evident in layered structures, with the ME voltage coefficient a factor of
10-30 higher than in bulk samples. Important findings of the studies in layered
composites are as follows. (i) The transverse coupling is stronger than the
longitudinal coupling. (ii) The strength of ME interactions is dependent on Zn
substitution with a maximum for x=0.4. (iii) Analysis of volume and static
magnetic field dependence of ME voltage coefficients reveal a weak coupling at
the ferromagnetic-piezoelectric interface. (iv) The interface coupling k
increases with Zn substitution and k versus x profile shows a maximum centered
at x=0.4. (iv) The Zn-assisted enhancement is attributed to efficient
magneto-mechanical coupling in the ferrite.
