Analysis of form factors observed with polarized neutrons; comparison with band structure calculations

Abstract

For the analysis of observed magnetic neutron form factors of transition metals and alloys different methods are being used. These methods are i) fitting of theoretical free-ion form factors to the experimental data, ii) Fourier analysis, as introduced by Moon, which does not require any a priori knowledge of the form factor but, instead, extracts its spin and orbital parts from the data, and iii) a modified version of ii) that properly takes into account the full symmetry of the crystal lattice. Spherical spin form factors appearing in i), ii) and iii) are compared with those based upon band structure calculations for Fe and Ni. It is found that only the results of iii) are in agreement with band theory. Since neither band theory nor method iii) leads to the existence of a uniform negative spin density this concept should be abandoned.