Microwave-Assisted Magnetization Reversal in Exchange-Coupled Composite Media Using Linearly Polarized Microwave Fields

We have experimentally demonstrated a microwave-assisted magnetization reversal (MAMR) in exchange-coupled composite (ECC) media using the linearly polarized microwave fields generated by an electrically shorted coplanar waveguide. The MAMR frequency exhibiting a maximum reduction of coercive field can be decreased using 16 nm-thick ECC media without the suppression of the thermal stability of magnetization. The threshold amplitude of microwave field required for the successful MAMR is only 3% of the anisotropy field of the medium. A splitting of ferromagnetic resonance spectrum, which suggests an appearance of stochastic MAMR, can be observed after applying microwave fields. The stochastic MAMR gives rise to the threshold behavior in the condition of microwave field amplitude needed for MAMR.