CONTROLLING CHAOS IN SPIN-WAVE INSTABILITIES

A microwave-pumped spin-wave-instability experiment is used to demonstrate that chaos can be controlled by a small periodic perturbation of an available system parameter, as recently proposed by Ott, Grebogi, and Yorke. The experiment is performed in an yttrium-iron-garnet sphere in the subsidiary-resonance configuration with a small modulation in the applied magnetic field. Observation of the Fourier spectrum of the low-frequency auto-oscillations and measurement of the attractor dimension and metric entropy demonstrate clearly that the chaotic attractor becomes periodic when the modulation frequency and amplitude are carefully chosen.