This letter reports the first detailed measurement of Mz, the component parallel to the effective field direction, when ferromagnets are excited by microwave fields at high power levels. It is found that Mz drops dramatically at the saturation of the main resonance. Simultaneous measurements of Mz 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 spinwaves excited above Suhl's instability. Similar behavior should be expected in spinwave emission by currents.
@article{arxiv.cond-mat/0405301,
title = {Magnetization reduction induced by nonlinear effects},
author = {G. de Loubens and V. V. Naletov and O. Klein},
journal= {arXiv preprint arXiv:cond-mat/0405301},
year = {2007}
}