Many-body effects at the Si L2,3VV Auger line shape: The case of Ca silicides.

Abstract

A joint experimental and theoretical analysis of the Si ${L}_{2}$,3VV line shape of ${\mathrm{CaSi}}_{2}$ and ${\mathrm{Ca}}_{2}$Si is presented. While the pp-two-hole contribution to the Auger line shape of the two Ca silicides is well described by a one-particle picture, strong hole-hole repulsive effects (U\ensuremath{\sim}3 eV) are present in the Auger process involving Si 3s states in ${\mathrm{Ca}}_{2}$Si. These correlation effects are consistently related to the quasiatomic nature of the Si 3s states in ${\mathrm{Ca}}_{2}$Si.