Nonlinear Effects above the Spin-Wave Instability Threshold

Abstract

An induction method at high-power level has been used to investigate effects above the first- and the second-order instability thresholds at ferromagnetic resonance. In the case of the first-order process a step on the hf magnetization pulse and low-frequency oscillations take place with a delay of about 30 μsec from the begining of the pulse. For the second order instability, the dependence of the uniform precession amplitude upon power level has three critical points, the first of which is the Suhl threshold, and the second the threshold of relaxation oscillations. The ``gap'' in the resonance curve suddenly arises in the third point. An attempt to explain some experimental results is made.