Magnetic and static lattice perturbation in dilute FeSb alloys from diffuse scattering of unpolarised and polarised neutrons

Abstract

The neutron diffuse elastic cross sections of dilute Fe1-cSbc alloys have been deduced from polarised and unpolarised neutron measurements. The magnetic cross sections are proportional to the concentration whereas the nuclear and the nuclear-magnetic cross sections present an abnormal concentration dependence. The data are analysed in terms of magnetic perturbation and static lattice distortions, the short-range order contribution being negligible. The magnetic perturbation corresponds to a model of 'isolated' impurities where the magnetic moment on antimony is small and negative (-0.2+or-0.3 mu B) and the average magnetic moment on iron increases with Sb concentration with a slope d mu Fe/dc=1.2 mu B atom-1. The results concerning the nuclear terms can be qualitatively explained by the contribution of large static lattice distortions around Sb atoms described in a Kanzaki force model. The unusual concentration variation is mainly attributed to the presence of direct defect-defect interactions.