Magnetically induced anisotropy in amorphous alloys of Fe-Ni-P-B

The uniaxial magnetic anisotropy Kuinduced during magnetic annealing has been determined for a series of amorphous alloys of the formula (FeyNi1-y)80P14B6. In contrast to the (Fe, Ni)80B20amorphous alloys previously reported, Kuin the present alloys has neither the composition dependence nor the temperature dependence predicted from simple pair order theory. The results strongly suggest the presence of a large contribution to the directional order anisotropy from the metalloids in the iron-rich amorphous alloys. The dependence of the uniaxial induced anisotropy on decreasing iron concentration can be accounted for by a decreasing contribution from the metalloids. A discrepancy in the temperature dependence of Kuat high anneal temperatures is attributed to the experimental problem of too slow a quench from the anneal temperature, compared to the rather fast kinetics of equilibration at temperatures below the anneal temperature.