Interpretation of x-ray magnetic circular dichroism and x-ray absorption near-edge structure in Ni

An interpretation of the spectral features in the Ni L-3 x-ray absorption n ear-edge structure and x-ray magnetic circular dichroism signals is present ed, based on both one-electron multiple-scattering and atomic-multiplet cal culations. Neither of these approaches is fully satisfactory. Although most of the observed features are reproduced by one-electron calculations, the pronounced peak about 3 eV above the edge is not. Conversely, the peal; at 6 eV and the smooth plateau just beyond are not reproduced by the multiplet calculations. The lack of the 3-eV feature is attributed to the neglect of many-body effects in the interaction between core hole and final-state d" configuration. The observed negative plateau between L-3 and L-2 edges is a ttributed to transitions to spin-polarized continuum epsilond states, and t he 6-eV peak, to multiple scattering paths of intermediate range and disapp ears fur Ni clusters smaller than 13 atoms. The necessity of both,one-elect ron and atomic-multiplet calculations to explain all features in the data d emonstrates the need for a combined approach.