Parametric excitation of magnetostatic modes in circular ferromagnetic films

Abstract
Magnetoexchange modes of a normally magnetized thin film with cos(νφ) and sin(νφ) azimuthal dependence are found to be excited through a process analogous to the second-order Suhl instability. If the modes are not degenerate, only one of the modes will be excited in the steady state above threshold. This effect has implications on the validity of the random-phase approximation inherent in the S theory commonly used to model spin-wave interactions in bulk media.