This study analyzes the loss peak frequency of an integrated ferromagnetic noise suppressor by evaluating the demagnetizing field. An integrated ferromagnetic noise suppressor is fabricated using a regular silicon process, and relation between the loss peak frequency and demagnetizing field is evaluated. The demagnetizing factor is calculated by approximating the magnetic film by a slender ellipsoid. Measurements of a fabricated on-chip noise suppressor reveal that the loss is maximized at 7 GHz, which is equal to the calculated ferromagnetic resonance (FMR) frequency. Then, the relation between the loss peak frequency and FMR frequency are discussed with some magnetic films in our previous works. The loss peak frequencies in coplanar lines of various magnetic films with different ratios of the film thickness to the signal line width agree well with the FMR frequency of magnetic films. This result reveals that the shift of the loss peak depends on the demagnetizing field over a wide frequency range. Consequently, the loss peak frequency of the integrated ferromagnetic noise suppressor can be controlled as a function of demagnetizing field in the magnetic film.Index Terms-Demagnetizing field, electromagnetic compatibility, electromagnetic noise suppressor, ferromagnetic resonance frequency, ferromagnetic resonance loss, magnetic films.

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We investigated the influence of magnetostriction on the damping constant (α) of 50-nm-thick NixFe1−x polycrystalline films, with x ranging from 0.66 to 0.86. In the experiments, α and the saturation magnetostriction (λs) were evaluated with high accuracy, which allowed for an interesting finding suggesting a simple relation between α and λs. In the range of positive λs, α slightly increases as x decreases, whereas α increases from 0.009 to 0.012 with increasing x for negative λs values. α reaches a minimum when λs is around zero at x = 0.78. These results demonstrate that different behaviors of α depend on positive or negative values of λs. Therefore, particular attention should be paid to the change in magnetoelastic properties and the deterioration of magnetic softness when adjusting α of magnetically soft films.

This paper reports the study on the damping constant α of Ni-Fe films using both one and two port type coplanar waveguide-ferromagnetic resonance (CPW-FMR) measurements, and compared these results with a conventional FMR (cavity-type FMR) measurement. In each CPW-FMR measurement, for the films thicker than 10 nm, each α becomes constant in the range of 0.012-0.014. On the other hand, for the film thickness less than 10 nm, α increases from 0.014 to 0.017 as the film thickness decreases, which may be attributed to structural inhomogeneity in the films. These results are in good agreement with those obtained from the cavity-type FMR measurement. On the basis of these results, it is pointed out that α of Ni-Fe films can be evaluated accurately by either of the CPW-FMR measurements. These results also mean that the one port type CPW-FMR measurement is more effective than the two port type CPW-FMR measurement for characterization of Ni-Fe films because the former method is simple and a stronger high frequency magnetic field can be generated.

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