Energy-loss near-edge structure (ELNES) and first-principles calculation of electronic structure of nickel silicide systems

Abstract

The electronic structures of nanometre-sized nickel silicide systems, Ni 2Si and NiSi, have been studied by energy-loss near-edge structure (ELNES) and first-principles band structure calculations. Experimental ELNES of Ni L 3- and Si L 2,3-edges could be explained well using theoretical spectra calculated for the ground state without the core hole, suggesting metallic properties for both silicides. It was shown that a slight difference in ELNES spectra of Ni 2Si and NiSi comes from the coupling among the Ni d and Si p, d states in the unoccupied bands. The density of states and the contour plots of all the valence electron densities for Ni 2Si, NiSi together with NiSi 2 show that Ni 2Si has the bond with the strongest covalent character between Ni and Si atoms and the most transition metal-like character of the Ni 3d band among the three silicides.