Temperature dependence of magnetic properties of a Co-based alloy in amorphous and nanostructured phase

The magnetic properties of a Go-based amorphous alloy (Metglas 2714A) are c ompared with those of the corresponding nanostructured alloy in the tempera ture range 30 K to the Curie temperature. A minimum appears in the permeabi lity versus temperature curve well below the Hopkinson peak for the amorpho us alloy. This minimum is ascribed to a form of induced anisotropy due to s tructural instabilities. In contrast, the alloy containing the nanostructur ed phase, having excellent soft magnetic properties, shows a maximum below the Hopkinson peak which is interpreted as a combination of the variations of the anisotropy and the saturation magnetization with temperature. The an isotropy field distribution is also evaluated in the low-temperature range for both the amorphous and nanostructured phase of the alloy. The most prob able anisotropy field for the nanostructured sample is ten times lower than that of the amorphous sample. (C) 1999 Elsevier Science B.V. All rights re served.