Composition dependence of magnetic moment and Curie temperature in amorphous (FexCo100-x)100-(y+z)SiyBzribbons

Composition dependence of the magnetic moment and Curie temperature in amorphous (FexCo100-x)100-(y+z)SiyBzribbons has been studied systematically with changing X, Y, and Z. A knee suggesting a peak was found in the magnetic moment vs. metalloid content curve for Fe-Si-B alloys, while the moment of Co-Si-B alloys decreases nearly linearly with increasing metalloid content. The moment of (FeCo)-Si-B alloys decreases monotonously with decreasing iron content. The behavior of the magnetic moment can be explained by the electron transfer from metalloid to the 3d band of transition metal atom. A clear peak in the Curie temperature vs. metalloid content curve was found not only for Fe-Si-B alloys but also for Co-Si-B alloys, contrary to the result for Co-P alloy. The Curie temperature of (FeCo)-Si-B alloys peaks for varying iron content independently of the amount of total metalloid contained in the alloys. These behaviors are discussed in the framework of the Slater-Bethe´s curve.