Microwave-assisted switching of NiFe magnetic microstructures

We have calculated, by either macrospin analytical method or micromagnetic numerical solving, the microwave assisted switching of a small rectangular platelet as a function of the amplitude and the frequency of a microwave excitation field. The spectral analysis of this phenomenon reveals that microwave-assisted switching is optimal for a rf frequency slightly lower than the linear magnetic resonance frequency measured at low level. Similar experimental results, obtained on 100 μm-scale NiFe structures reveal the same tendency. Switching time for such a process was obtained from calculations that show that sub-nanosecond switching times require combinations of large dc (direct current) and rf (radio frequency) magnetic fields.