NONLINEAR RADIATION DAMPING OF PARAMETRICALLY EXCITED SPIN-WAVES

We consider the process of microwave parametric excitation of spin wav es in a resonator. The interaction of the resonator cavity photon with the parametric magnon pair is expected to cause additional nonlineari ty: nonlinear radiation damping which is proportional to the quality f actor Q of the resonator. Estimations of this positive nonlinear magno n relaxation in ferromagnets and antiferromagnets (for electronic and nuclear spin waves, magnetoelastic waves) show that it can play an imp ortant role in forming the stationary state. The threshold of the auto oscillations of microwave absorption in a ferromagnet is found to incr ease with increasing Q.