Magnetostatic wave propagation in YIG double films

Using the technique of surface permeabilities, an expression is derived for the dispersion of a magnetostatic wave propagating in two close proximity magnetic films. Two modes of propagation are identified respectively as the symmetric and antisymmetric modes from the symmetry of the rf magnetic field. Useful group delay behavior is shown to result from films of equal thickness. Some measurements are reported using two Yttrium Iron garnet films sandwiching simple single finger transducers. Difficulties in exciting the symmetric forward volume mode are explained in terms of the coupling coefficients for these double film structures.