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

The ferromagnetic resonance linewidth of Fe73.5CuNb3Si13.5B9 melt-spun ribb ons bas been investigated as a function of annealing temperature. Fe73.5CuN b3Si13.5B9 possesses an ultrafine grain structure whicli can be altered by suitable annealing to exhibit a combination of excellent soft magnetic char acteristics and high Saturation induction. It is a ferromagnetic metal cons isting of crystallites whose anisotropy axes are randomly oriented and whic h may interact with each other via exchange or dipolar fields. When anneale d at moderate temperatures, Fe73.5CuNb3Si13.5B9 is characterized by an extr emely low coercive field, and is useful in magnetic cores and memories, At a critical temperature (similar to 600 degreesC), the grain size rapidly in creases with annealing temperature. This onset of crystallization is accomp anied by a relatively abrupt increase in the FMR linewidth, the magnetic an isotropy field, and the coercive field. We extend the scaling arguments of Herzer to explain these obviously related phenomena. Published by Elsevier Science B.V.