Bonding in metal disilicides CaSi2through NiSi2: Experiment and theory

Abstract

Synchrotron radiation photoemission experiments with the disilicides of Ti, V, Nb, Cr, Fe, Co, and Ni are combined with self-consistent augmented-spherical-wave calculations of the density of states for metal silicides from Ca-Si to Cu-Si. These results demonstrate the importance of silicon $p$—metal $d$ bond formation extending to ∼6 eV below $E_F$ for all transition metals. Experiment and theory are combined to show the movement of the nonbonding $d$ states from above $E_F$ for Ca-Si to well below $E_F$ for Cu-Si. At the same time, the antibonding Si $p$ and Si $s$ states are shown to be relatively insensitive to the particular metal atom in the silicide series.