Magnetostatic waves in nonuniform bias fields including exchange effects

The method of expansion in normal spin wave modes has been extended to the case of a two-dimensional nonuniformly magnetized ferrite with the effects of exchange included. The direction of the nonuniform bias field is normal to the plane of the ferrite. Using this method, a number of solutions (both exact and approximate) to the linearized magnetostatic equations have been obtained. Correspondence is pointed out between the new solutions, the spin wave theory of Eshbach, and the magnetostatic theory of Morgenthaler. These solutions further elucidate the role of exchange in magnetostatic wave propagation in nonuniform fields.