Reduction of the spin-wave damping induced by nonlinear effects

This paper reports a detailed measurement of M-z, the component parallel to the effective field direction, when ferromagnets are excited by microwave fields at high power levels. It is found that M-z drops dramatically at the saturation of the main resonance. Simultaneous measurements of M-z and absorption power show that this drop corresponds to a diminution of the spin-lattice relaxation rate. These changes are interpreted as reflecting the properties of longitudinal spin waves excited above Suhl's instability.