We report a study of the spin moment in Fe 3 O 4 as a function of temperature using spin-dependent Compton scattering. Magnetic Compton profiles and spin moment values were obtained either side of the Verwey transition for applied magnetic fields of 2.5 and 7 T. The orbital moments, determined by comparison with bulk magnetometry, are almost fully quenched. No evidence of any anomalies in the spin or orbital moments at the Verwey transition was observed. The magnetic Compton profiles have the characteristic shape for Fe 3d electrons at all temperatures with no changes in the degree of anisotropy across the Verwey transition. Our data are consistent with the highly spin-polarized electronic structure expected for bulk Fe 3 O 4 .

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We report on a new method to determine the degree of bulk spin polarization in single crystal Co (1−x) FexS2 by modeling magnetic Compton scattering with ab initio calculations. Spin-dependent Compton profiles were measured for CoS2 and Co0.9Fe0.1S2. The ab initio calculations were then refined by rigidly shifting the bands to provide the best fit between the calculated and experimental directional profiles for each sample. The bulk spin polarizations, P , corresponding to the spinpolarized density of states at the Fermi level, were then extracted from the refined calculations. The values were found to be P = −72 ± 6% and P = 18 ± 7% for CoS2 and Co0.9Fe0.1S2 respectively. Furthermore, determinations of P weighted by the Fermi velocity (vF or v 2 F ) were obtained, permitting a rigorous comparison with other experimental data and highlighting the experimental dependence of P on vF .