ON-OFF INTERMITTENCY IN A HIGH-DIMENSIONAL MODEL OF RANDOMLY DRIVEN PARALLEL PUMPING

A model of parallel pumping with many interacting parametric spin-wave pairs is investigated numerically. Two ways of obtaining on-off inter mittency in the time series of absorption are discussed: random or cha otic modulation of the rf field amplitude or of the de field, slow in comparison with the rf field frequency. If the possibility of thermal excitation of spin waves is neglected, only one spin-wave pair is exci ted above the intermittency threshold and exhibits bursts. In the oppo site case, a phenomenon of widening of the phase space in the presence of thermal noise is observed: a packet of parametric spin waves is ex cited with frequencies close to half the pumping frequency. This modif ies quantitatively, but not qualitatively the characteristics of on-of f intermittency in the presence of thermal noise. (C) 1997 Elsevier Sc ience Ltd.