Resonant X-ray Scattering Study of Anisotropic Charge Distribution of Gd Ions in GdB 4

Temperature dependence of anisotropic tensor susceptibility (ATS) scattering intensities of GdB4 were measured near L -edges of Gd to investigate how spin ordering affects ATS. ATS scattering intensities for L 2 - and L 3 -edges show different temperature dependence below T N . At L 3 -edge the intensities reflect spin order parameter while intensities at L 2 -edge do not show noticeable change. The difference is explained in terms of spin-orbit coupling and isotropic distribution of spin-polarized 5 d states of Gd ions. Above T N ATS scattering intensities demonstrate that thermal motions enhance charge distribution anisotorpy of Gd 5 d states in paramagnetic phase.