Intermittencies in the presence of symmetry in spin-wave experiments.

Abstract

Intermittent auto-oscillations of the dynamic magnetization prior to chaotic behavior have been observed in microwave transverse pumping of the subsidiary resonance in a yttrium iron garnet sphere at room temperature. These intermittencies appear simultaneously with a period-doubling bifurcation. Diversely from the type-III Pomeau-Manneville intermittency, the observed chaotic bursts do not seem to be associated with an increase in the amplitude of the subharmonic mode, which remains essentially constant during the laminar phases. From time-series data the distribution of the laminar period lengths has been measured, and a return map has been constructed. These results are in reasonable agreement with a theory based on a symmetrical mapping that describes the dynamics of Lorenz-type flows. Experimental evidences of new scenarios for the onset of chaos are also presented.