Influence of Gd on the magnetic properties of amorphous (Fe1-xGdx)80B20

Amorphous (Fe1-xGdx)(80)B-20 alloys have been prepared by melt spinning technique and their magnetic properties have been studied. The Gd moment at 10 K is found to be 7 mu(B) which agrees with the theoretical value indicating a collinear spin structure. The magnetic compensation at 10 K occurs for x close to 0.195. The mean-field theory has been used to explain the temperature dependence of the magnetization. The exchange interactions between Fe-Fe, Fe-Gd and Gd-Gd atom pairs have also been evaluated. From an analysis of the approach to saturation magnetization, the local random anisotropy constant K-L has been extracted. It is found that K-L decreases with increasing Gd concentration. This result suggests that the substitution of Fe with Gd seems to favor the increase of magnetic order by reducing the random anisotropy.