The extent of localisation of the Fe moment in Y(Fe1-xAlx)2and Zr(Fe1-xAlx)2-a comparison of the magnetic properties

Abstract

Magnetisation, AC and DC susceptibility measurements of the pseudobinary systems Y(Fe1-xAlx)2 and Zr(Fe1-xAlx)2 are reported. On substituting Al for Fe the transition from ferromagnetism to paramagnetism in Y(Fe1-xAlx)2 is found to be dominated by freezing phenomena which are characteristic of a cluster-glass regime (0.1<x<0.35), while such freezing phenomena are not observed around the critical concentration for ferromagnetism (xc=0.55) in Zr(Fe1-xAlx)2. The analysis of the DC susceptibility data yields finite paramagnetic Curie temperatures and mu eff values up to about 90% Al for Y(Fe,Al)2, whereas for Zr(Fe,Al)2 both mu eff and theta exhibit the usual concentration dependence vanishing above xc. From these results the authors deduce that the Fe moment can be regarded as more delocalised in the Zr system than in the Y pseudobinaries which may be attributed to a larger degree of hybridisation of the d electrons in the Zr compounds when compared with those of Y.