Competition between pumping and damping in microwave-assisted magnetization reversal in magnetic films

This paper reports the demonstration of microwave-assisted magnetization reversal (MAMR) in large-damping materials and the observation of a saturation effect for the enhancement in the MAMR process. The experiments were carried out on Fe70 Co30 thin films. A reduction in the switching field was observed in the presence of microwaves. The level of such a reduction depends on the frequency and power of the microwaves. With increasing the microwave duration, the switching field decreases first but then approaches a lower limit. This saturation of the switching field reduction was interpreted in terms of the pumping-damping competition. The interpretation was supported by the measurements of the switching field as a function of the microwave duration for different conditions.