Collective Electron Ferromagnetism, III. Relative Magnetization of Ferromagnetic Alloys

Abstract

Here is studied the relative magnetization (ζ₀) at absolute zero of temperature of ferromagnetic alloys composed of the first transition metals (except manganese). Based on Stoner’s representation of the reduced inverse susceptibility vs reduced temperature curves, ζ₀ values are found from the measured values of saturation magnetization at absolute zero (σ₀), of the Curie temperature (θ) and of the mass susceptibilities above the Curie temperature (χ). With the estimated values of ζ₀, the number of carriers of ferromagnetism is plotted against the number of outer electrons. It is found from experiments on some body-centered cubic alloys of iron that ζ₀ is not much less than unity for these alloys, and hence it is concluded that for body-centered cubic alloys the lower half of the d band is not responsible for ferromagnetism. A similar analysis for face-centered cubic alloys shows that ζ₀ values of face-centered cubic cobalt-iron and nickel-iron alloys decrease gradually as the iron content increases, and the number of carriers of ferromagnetism becomes greater than 2 per atom near the composition of the body- and face-centered cubic boundary. Some other examinations are also made on the band theory of ferromagnetism in relation to the neutron diffraction experiments made by Shull and Wilkinson.