Stripline ͑SL͒, vector network analyzer ͑VNA͒, and pulsed inductive microwave magnetometer ͑PIMM͒ techniques were used to measure the ferromagnetic resonance ͑FMR͒ linewidth for a series of Permalloy films with thicknesses of 50 and 100 nm. The SL-FMR measurements were made for fixed frequencies from 1.5 to 5.5 GHz. The VNA-FMR and PIMM measurements were made for fixed in-plane fields from 1.6 to 8 kA/ m ͑20-100 Oe͒. The results provide a confirmation, lacking until now, that the linewidths measured by these three methods are consistent and compatible. In the field format, the linewidths are a linear function of frequency, with a slope that corresponds to a nominal Landau-Lifshitz phenomenological damping parameter ␣ value of 0.007 and zero frequency intercepts in the 160-320 A / m ͑2-4 Oe͒ range. In the frequency format, the corresponding linewidth versus frequency response shows a weak upward curvature at the lowest measurement frequencies and a leveling off at high frequencies.
Abstract-This paper describes a classical version of the two-magnon model of ferromagnetic resonance linewidth in inhomogeneous magnetic thin films. The ferromagnetic resonance line broadening due to inhomogeneity is described in terms of film properties and the statistical properties of the inhomogeneity. Analytical results for the case of ultrathin films in the limit of zero damping are compared with numerical results computed with finite damping.
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