The effective Curie-Weiss constant of ferromagnetic metals and alloys

Abstract

Experimental data for the Curie-Weiss constant and the saturation magnetization of a wide variety of ferromagnetic substances are used to calculate respective values for the numbers of magnetic carriers, q c and q s . A plot of the ratio q c / q s as dependent on the Curie temperatures reveals two branches. For one of these q c / q s is about 1, and for the other q c / q s > 1. The first branch corresponds to substances, such as gadolinium and the com pound MnSb, which accord with a purely localized model of ferromagnetism . The second branch corresponds to substances, such as nickel and its alloys, dilute alloys of palladium and the compounds Sc 3 In and ZrZn 2 , according with the ‘intermediate model’ (Edwards 1962), which reduces in the present context to the collective electron model of ferromagnetism. Calculations of a quantity closely related to the ratio q c / q s have been made for different forms of the density of states curve, including one with a sharp peak. The general forms of the theoretical curves are in satisfactory qualitative agreement with the form of the second branch in the plot of the experimental results. The experimental data for the dilute palladium alloys are also used to derive the variation with iron, cobalt and nickel content of the number of holes per atom and the relative magnetization at 0 °K.