Magnetic-moment distribution and environmental effects in dilute iron-based alloy with V, Cr, and Mn impurities

Abstract

The measurements of polarized neutron elastic, diffuse scattering on dilute iron-based alloys with about 1 and 2 at.% of Cr, V, and Mn impurities are reported. The measurements have been performed at room temperature using a polarized neutron beam with wavelength of 4.25 \AA{}. The data indicate existence of a large magnetic moment on impurity atoms at about 1 at.% concentration, coupled antiparallel to the bulk magnetization. The observed values of average impurity moment agree very well with theoretical calculations done by Campbell and Gom\'es on the basis of Friedel's model of virtual bound-state formation in these alloys and support the idea of localized impurity states in the dilute limit. The value of the average impurity moment decreases rapidly with increasing alloy concentration, whereas the iron moment is nearly constant with a slight tendency to increase. The environmental effects are mostly confined to the first shell of atoms and depend on the kind of impurity and its concentration. The data are compared with coherent potential-approximation calculations for these alloys.