Critical Magnetic Scattering of Neutrons by Iron

Abstract

The experimental results of Wilkinson and Shull for the small-angle magnetic scattering of 0.9 A neutrons from iron at temperatures close to the Curie point are analyzed in terms of the instantaneous correlation between pairs of spins of the iron atoms. Fourier inversion of the angular distribution of the scattering gives the spatial dependence of the spin-spin correlations, while their temperature dependence follows from the temperature variation of the angular distributions. The correlation functions so obtained are compared with the asymptotic form predicted by statistical mechanics and show consistency with the measured values of the paramagnetic susceptibility for iron above the Curie temperature.