Magnetic evolution of the amorphous and nanocrystalline phases and interphase coupling during the crystallization of Fe87Zr6B6Cu:: A ferromagnetic resonance study

We present results of ferromagnetic resonance measurements on the alloy Fe87Zr6B6Cu. These show the changes occurring in the sample, both magnetically and structurally, during the crystallization process. In this alloy the amorphous phase gradually crystallizes, forming nanocrystallites of alpha-Fe in a remaining ferromagnetic amorphous matrix. Results show evidence of a disordered and Fe-rich interphase region surrounding the Fe crystallites. This interphase region initially grows along with the growth of the Fe nanocrystals. However, in the latter stages of the Fe nanocrystallization, this phase also crystallizes into the Fe phase and other crystalline phases, and disappears at the end of the Fe crystallization and the beginning of second crystallization. Evidence of an interface localized spin wave mode at the boundary between the amorphous ferromagnetic and Fe phases in the early stages of crystallization is also observed. At higher annealing temperatures, we observe another resonance absorption feature. This is due to the onset of the second stage of crystallization, where FeZr and iron-boride phases form. The results of the ferromagnetic resonance are analyzed in a multiphase regime, where the importance of the magnetic coupling between the various magnetic phases is evident. A minimum of the in-plane anisotropy is found to coincide with the softest magnetic properties of this alloy. [S0163-1829(98)03441-9].