Spin-wave instabilities in large-scale nonlinear magnetization dynamics - art. no. 217203

The stability of large magnetization motions in systems with uniaxial symme try subject to a circularly polarized radio-frequency field is analytically studied. Instability conditions valid for arbitrary values of the amplitud e and frequency of the driving field are derived. In the limit of small mot ions, these conditions yield Suhl's theory of spin-wave instabilities for t he case of ferromagnetic resonance. It is shown that the input powers capab le of inducing spin-wave instabilities are bounded from both below and abov e, so that large enough motions are always stable. In addition, it is demon strated that stability of uniform motions depends on their preparation hist ory.