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Precise determination of the spectroscopic g-factor using broadband ferromagnetic resonance spectroscopy



Justin M. Shaw, Hans T. Nembach, Thomas J. Silva, Carl T. Boone


We demonstrate that the spectroscopic g−factor can be determined with high precision and accuracy by use of a broadband ferromagnetic resonance measurements and applying an asymptotic analysis to the data. Spectroscopic data used to determine the g−factor is always obtained over a finite range of frequencies, which can result in significant errors in the fitted values of the spectroscopic g−factor. We show that by applying an asymptotic analysis to broadband datasets, precise values of the intrinsic g−factor can be determined with errors well below 1 %, even when the exact form of the Kittel equation (which describes the relationship between the frequency and resonance field) is unknown. We demonstrate this methodology with measured data obtained for sputtered Ni80Fe20 (“Permalloy”) thin films of varied thicknesses, where we determine the bulk g−factor value to be 2.109 {plus or minus} 0.003. Such an approach is further validated by application to simulated data that includes both noise and an anisotropy that is not included in the Kittel equation that was used in the analysis. Finally, we show a correlation of thickness and interface structure to the magnitude of the asymptotic behavior, which provide insight into additional mechanisms that may induce deviations from the Kittel equation.
Journal of Applied Physics


Ferromagnetic resonance, spin moment, orbital moment, g-factor, permalloy, NiFe


Shaw, J. , Nembach, H. , Silva, T. and Boone, C. (2013), Precise determination of the spectroscopic g-factor using broadband ferromagnetic resonance spectroscopy, Journal of Applied Physics (Accessed May 18, 2024)


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Created December 27, 2013, Updated June 2, 2021