Sum rules and figures-of-merit on the microwave permeability of nanocrystalline microwires

The microwave permeability spectra of three nanocrystalline microwires were investigated, and dynamic magnetization Mμ(F) was determined from these spectra. An experimental verification of the theoretical prediction that this quantity was lower than the saturation magnetization was carried out, and it was further shown that the theoretical result provided straightforward guidelines for the conception of high-permeability materials, including successful tradeoffs between a higher resistivity and an increased saturation magnetization. Mμ(F) was determined to be an appropriate figure-of-merit for several applications, including high-frequency noise suppressors.