Observation of period doubling and chaos in spin-wave instabilities in yttrium iron garnet
Ferromagnetic resonance in a polished 0.047-cm-radius sphere of gallium-doped yttrium iron garnet is studied at 1.3 GHz in a magnetic field of 460 G. A second-order Suhl instability is observed, owing to the nonlinear coupling of the precessing uniform magnetization with spin waves. This is detected by the onset of auto-oscillations of the magnetization. One of these modes with frequency roughly-equal16 kHz corresponds to the lowest spherical dimensional resonance of a packet of spin waves of small wave vector and long lifetime (roughly-equal10/sup 3/ cycles). From real-time signals, spectral analysis, and return maps this mode is found to display chaotic dynamics as the driving rf field is increased: thresholds for the onset of period-doubling bifurcations, chaos, and periodic windows. Some observed return maps bear resemblance to the two-dimensional area-preserving quadratic map of Henon. The system has several attractors and displays ''solid-state turbulence,'' analogous to that in fluids.
- Research Organization:
- Department of Physics, University of California, Berkeley, California 94720 and Materials and Molecular Research Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
- OSTI ID:
- 6615574
- Journal Information:
- Phys. Rev. A; (United States), Vol. 29:2
- Country of Publication:
- United States
- Language:
- English
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