Monodomain Design and Permeability Study of High-Q-Factor NiCuZn Ferrites for Near-Field Communication Application

For application in near-field communication (NFC) systems, monodomain NiCuZn ferrite has been prepared by the conventional solid-state reaction method. The results show that the monodomain design is effective; the Q factor of this kind of sample with 0.3 wt.% Co 2 O 3 doping could be as high as 118.19. To obtain guidelines for preparing high-quality materials, the magnetic spectra of monodomain ferrite samples are studied via a numerical fitting method. According to the results of this permeability spectra fitting, the magnetic spectra of our prepared samples are mainly determined by the static spin susceptibility K s , spin resonance frequency ω 0 , and relaxation frequency ω r . Specifically, we find that ω r varies with the frequency of the external field f . Furthermore, we demonstrate that Co 2 O 3 influences the relationship between ω r and the frequency of the external field. According to theoretical expectations, a higher Q factor at frequency of 13.56 MHz could be obtained by using an appropriate Co 2 O 3 content.