  We study the propagation of surface spin waves in two wave guides coupled
through the dipole-dipole interaction. Essential for the observations made here
is the magneto-electric coupling between the spin waves and the effective
ferroelectric polarization. This allows an external electric field to act on
spin waves and to modify the band gaps of magnonic excitations in individual
layers. By an on/off switching of the electric field and/or varying its
strength or direction with respect to the equilibrium magnetization, it is
possible to permit or ban the propagation of the spin waves in selected
waveguide. We propose experimentally feasible nanoscale device operating as a
high fidelity surface wave magnonic gate.
