We present detailed results of studies of chaos and chaotic transients involving spin waves in an yttrium iron garnet sphere. We drive the ferromagnetic resonance of this system at the 6rst-order Suhl instability using driving frequencies between 2.0 and 3.4 GHz. In some regions of parameter space we see chaotic transients, while in others we see quasiperiodic oscillations or stable chaos. We characterize these states by various means, such as dimension or amplitude. We also present some results of a three-spin-wave-mode calculation based on the Landau-Lifshitz equation. This calculation produces phenomena similar to some of those seen in the experiment but is not sufficient to reproduce all the behavior that we see. We believe that a calculation involving more spin-wave modes is necessary to reproduce many of our experimental results.

One of the classic problems in the study of nonlinear dynamics has been the diode resonator. Previous work with the diode resonator sought to explain the causes of period doubling and chaos, and often used simplified models. This paper instead seeks to link the onset of nonlinear dynamical effects to measurable parameters by comparing experiments and numerical models.

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When thin films of yttrium iron garnet (YIG) are placed in a magnetic field and driven at microwave (rf) frequencies, nonlinear interactions within the material cause the normal microwave spin precession to be modulated at lower frequencies. We measure these lower frequency (kHz) signals at two spatially separated locations on the YIG film and use linear and nonlinear analysis to study the functional dependence of the spin dynamics at one location on the spin dynamics at the other location. We see dynamical states where nonlinear analysis can detect a functional dependence that the linear analysis fails to reveal.