POLARIZED-NEUTRON STUDY OF MAGNETIC MOMENT DENSITY IN ANTIFERROMAGNETIC CUSO4

A determination of the spatial distribution of magnetic moment density in the antiferromagnet CuSO4 has been made by means of the polarized-neutron-beam technique. Data collected at 4.5°K for two zones showed very large deviations in a number of cases from a smooth form-factor curve. Fourier transforms of the data revealed regions of substantial magnetic moment density (0.05-0.1B) localized mainly between the Cu2+ ions and the SO42- groups. The observation of appreciable concentrations of density in positions removed from the Cu2+ sites suggests the presence of relatively strong superexchange interactions through the SO42- groups, as indicated also by the relatively high Néel point of about 36°K. In order to permit accurate analysis of the polarized-beam data, the crystal-structure parameters of CuSO4 at 77°K were refined by least-squares analysis, and the errors in the calculated nuclear-structure factors were evaluated. © 1969 The American Physical Society.