Measuring anisotropy field of patterned soft magnetic films by anisotropic ferromagnetic resonances.

Patterned magnetic films have been applied widely in communication technology for meeting the development of miniaturization and high frequency. However, there has been some debate about the measuring of the anisotropy field, which is significant for deciding the electromagnetic performance. In the paper, we proposed the measurement of the anisotropy field using anisotropic ferromagnetic resonances in patterned permalloy magnetic films. The anisotropy in patterned permalloy with different magnetic stripe widths can be observed qualitatively by the hysteresis loop along in-plane x and y directions, which induces the anisotropic ferromagnetic resonant behaviors. The anisotropy field can be calculated quantificationally by fitting the Kittel equation when the single resonant peak appears under applied magnetic fields. The values of the anisotropy field obtained by anisotropic ferromagnetic resonances are on the lower side to compare with the ones obtained by the energy difference between easy anis and hard axis. Our results can provide an extra method for measuring the anisotropy field, which can be useful for designing electromagnetic devices and potential applications in next-generation wireless communication.