Chaos and chaotic transients in an yttrium iron garnet sphere

Abstract

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.

On-Off Intermittency in Randomly Driven Nonlinear Ferromagnetic Resonance

“…[15]) has been for almost fifteen years a useful tool in the -study of nonlinear phenomena, including, e.g. multistability [16], autooscillations of the magnetization and chaos [16][17][18][19][20][21][22], hyperchaos [23], control of chaos [24,25], various types of intermittency [26][27][28], chaotic transients [29,30] etc. Less attention was devoted to the case On-Off Intermittency in Randomly Driven ... 39 in which the rf fleld amplitude varies stochastically in time, e.g.…”

Period doubling toward chaos in a driven magnetic macrospin

“…But, the geometry of this study, although theoretical, differs from that of previous studies in the shape and type of the material, as well. Most of the earlier works [8,9,11,12], both experimental and theoretical, dealt with spheres of yttrium iron garnet (YIG). This was used because high quality YIG spheres were available with very small damping parameters allowing the nonlinear behavior to be obtained with small driving fields.…”

“…It is used as a model for gyromagnetic precession and dissipation, and in the analysis of most ferromagnetic media including studies of ferromagnetic resonance [1] and magnetization switching in thin films [2]. One area of research, along the lines of that which is studied here, has focused on nonlinear magnetic motions driven by currents [3,4] or on chaos produced by a driving magnetic field [5][6][7][8][9][10][11][12].…”

Noise-robust synchronized chaotic communications

“…It is possible in nature to have chaotic systems where motion occurs on very different time scales; in ferromagnetic resonance experiments in Yttrium Iron Garnet, for example [15]- [18], the spin magnetic moment of the material responds at frequencies in the range of 10 9 Hz and 10 3 Hz. For a previous paper, a chaotic circuit was designed which also had motion on two different time scales [19].…”