Ferromagnetic resonance studies of multiphase ferromagnets

The theory of ferromagnetic resonance (FMR) and spin-wave resonance (SWR) i s presented for the general case of multiphase ferromagnets, and applied to nanocrystalline materials, where nanometre size ferromagnetic crystals are embedded in an amorphous ferromagnetic phase which has a different magneti zation. The possible existence of spin-wave modes or interface localised mo des is taken explicitly into account for the first time in mixed phases. Th e magnetic evolution of the nanocrystalline and amorphous phases in Fe87Zr6 B6Cu1 glasses has been studied by FMR using the above theory. Resonance lin es from the alpha -Fe nanocrystals, the surrounding amorphous phase and a d isordered Fe-rich interface are observed and interpreted. At higher anneali ng temperatures further resonance lines appear as Fe-Zr and Fe-B hard magne tic phases precipitate from the amorphous matrix. (C) 2000 Elsevier Science B.V. All rights reserved.