  In the first part of this work we calculate the high frequency
magnetoelectric susceptibility of a simultaneously ferroelectric and canted
antiferromagnetic (also know as weak ferromagnetic) thin film with
magnetostrictive magnetoelectric coupling. We show that a dynamic coupling
exists between the ferroelectric and optic antiferromagnetic excitations. In
the second part of the paper, we calculate using an effective medium method the
susceptibility of a heterostructure comprising alternating thin films of such a
material together with a ferromagnet. Dipolar magnetic fields serve to couple
the ferromagnetic and optic antiferromagnetic modes, which in turn couples the
ferromagnetic and ferroelectric excitations. This provides a mechanism for
creating "electromagnon" modes in the microwave regime which may be useful for
applications.
