AIP Digital Archive
The electronic configuration of trivalent Pu is nominally a 5f5 state in which there is a strong cancellation of the L (orbital) and S (spin) components in the J=5/2 ground state. This leads to small g factors and magnetic moments, and to unusual neutron magnetic form factors f(Q) with maxima at Q values greater than zero. We present here the results of form-factor measurements (taken on the polarized-neutron diffractometer at the ILL) on single crystals of PuSb, PuTe, and PuFe2. These results show that the form factor, which is a measure of the magnetization density of the 5f electrons around the Pu nucleus, is sensitive to the degree of localization of the 5f electrons. For example, in PuSb the 5f electrons are well localized and the form factor is in good agreement with the predictions of intermediate coupling and crystal-field theory. In PuTe f(Q) falls monotonically from a maximum at Q=0, indicating an almost spin-only system. This is produced by wide 5f bands, which give rise to the observed T-independent magnetic susceptibility. In PuFe2, however, a large maximum occurs in f(Q). We believe this arises from strong hybridization of the 5f and 3d Fe electrons, which leads to a reduction in the Pu orbital component.
Type of Medium: