General spin wave instability theory for anisotropic ferromagnetic insulators at high microwave power levels

The theory of spin wave instability for ferromagnetic insulators is extended to include generalized anisotropy based on a tensor formulation of the static and dynamic effective fields. The formalism is set up for saturated magnetic ellipsoids and a general microwave field configuration. Both first- and second-order processes are considered. The analysis yields working formulae for the threshold microwave field amplitude evaluations and critical mode determinations. An example is given for first-order processs in a thin disk with easy plane anisotropy. (C) 2002 Elsevier Science B.V. All rights reserved.