Synthesized magnetostatic resonances in a nonuniformly biased thin disk without conducting boundaries

Magnetostatic resonances of a nonuniformly biased thin ferrite disk, that is surrounded by free space and magnetized to saturation along the normal to its plane, are analyzed for the conditions of weak to moderate radial gradients of arbitrary form. The circular disk is modelled as a highly oblate spheroid and the resonances studied are quasi-two-dimensional in character. The results reveal the manner in which mode properties are affected by both the bias gradients and electromagnetic corrections and allow the synthesis of modes with pre-specified characteristics, such as frequency, rf energy distribution and velocity of energy circulation. Because control of that velocity not only affects group delay of signals propagating through the mode but also the rf energy density, we predict that the onset of nonlinear effects due to parametrically-induced spin waves should be governed by instability thresholds that are gradient-controllable.