Electrical detection of microwave assisted magnetization switching in a Permalloy microstrip

Microwave assisted magnetization switching has been investigated in a nonelliptic Permalloy microstrip, using radio frequency magnetic fields h applied in-plane perpendicular to the long axis of the strip. In low power excitations, H(s) decreases almost linearly with increasing h; this can be qualitatively understood by introducing an susceptibility chi(yy) that links the dynamic magnetization inside the microstip to the h field outside the microstip. However, at high frequencies, H(s) no longer decrease with increasing h when this latter field exceeds a critical value. We suppose such saturation effects could attribute to the nonlinear ferromagnetic resonance caused by high power excitations.