Ferromagnetic resonance in nanocrystalline Fe73.5CuNb3Si13.5B9 (Finemet)

The ferromagnetic resonance linewidth of Fe73.5CuNb3Si13.5B9 melt-spun ribbons bas been investigated as a function of annealing temperature. Fe73.5CuNb3Si13.5B9 possesses an ultrafine grain structure whicli can be altered by suitable annealing to exhibit a combination of excellent soft magnetic characteristics and high Saturation induction. It is a ferromagnetic metal consisting of crystallites whose anisotropy axes are randomly oriented and which may interact with each other via exchange or dipolar fields. When annealed at moderate temperatures, Fe73.5CuNb3Si13.5B9 is characterized by an extremely low coercive field, and is useful in magnetic cores and memories, At a critical temperature (similar to 600 degreesC), the grain size rapidly increases with annealing temperature. This onset of crystallization is accompanied by a relatively abrupt increase in the FMR linewidth, the magnetic anisotropy field, and the coercive field. We extend the scaling arguments of Herzer to explain these obviously related phenomena. Published by Elsevier Science B.V.