Fractal Structure of Strange Attractor at the Subsidiary Resonance in Yttrium Iron Garnet

Abstract

Transverse pumping at the first-order Suhl instability in YIG has been performed at a pumping frequency of 3.3 GHz at 4.2 K. Above the spin-wave instability threshold, period-doubling cascades and chaotic auto-oscillations are observed. From time-series data, return maps, fractal dimensions, phase space portraits of strange attractors, two-dimensional Poincare sections, and singularity spectrum f (α) are obtained. The Poincare sections of the phase space trajectories exhibit the stretching and folding which are characteristics of strange attractors. At the onset of chaos, the f (α) spectrum is consistent with the universal one.