Subsidiary Absorption above Ferrimagnetic Resonance

The interaction between magnetostatic modes and spin waves was first discussed by Suhl [H. Suhl, J. Phys. Chem. Solids 1, 209 (1957)] and was shown to be the source of nonlinear effects at high power in ferrimagnetic resonance. It is the purpose of this article to extend Suhl's results on the threshold for subsidiary absorption to dc magnetic fields greater than that required for ferrimagnetic resonance. Some numerical results on the threshold for subsidiary absorption are presented for shapes other than spheres and for magnetostatic modes other than the uniform precession on a sphere. Some general conclusions regarding the shape dependence of nonlinear effects are stated. The theory is then compared with experimental results on YIG and MnZn ferrite.