Nonlinear microwave-magnetic resonator operated as a bistable device

The excitation of large amplitude spin waves causes a shift in the resonance frequency of a ferrite resonator towards higher frequency values. Using this shift, a resonator can be designed to operate in a bistable mode where the history of the input power determines the output power. A theoretical calculation for a resonator with a linewidth of 1.5 MHz, measured at 10 GHz, predicts a discontinuous jump in output power by a factor of about 3.5 as the input power is increased to about 0.7 mW. The phenomenological model that describes the bistability also provides an explanation for the foldover of ferromagnetic resonance curves at high input power levels. An appropriate choice for the operating frequency ensures that the estimated input power required to observe the bistable behavior is below the predicted threshold power for spin-wave auto-oscillations at the main resonance.