INTERMITTENCY OBSERVED IN YTTRIUM-IRON-GARNET UNDER PARALLEL PUMPING

Parallel pumping experiments in yttrium iron garnet have been performe d at a pumping frequency 9.45 GHz and at a temperature 4.3 K. Above th e spin-wave instability threshold, auto-oscillations of magnon amplitu de are observed. Just above the onset of the auto-oscillations, signal has character of intermittent. From time-series data, Poincare return maps and distribution of laminar period lengths are obtained. These r esults are in agreement with the theory based on symmetrical mapping t hat describes the dynamics of Lorentz type flows. Bifurcation paramete rs obtained by the best fit with the theoretical relation are presente d as a function of the microwave power. Relationship between the avera ge of the laminar lengths and the bifurcation parameter is in good agr eement with the theoretical prediction.