RESONANT PHOTOEMISSION-STUDY OF TERNARY TRANSITION-METAL SILICIDES

The electronic structure of three ternary transition-metal silicides Ti4M4Si7 (M=Ni,Co) and TiFeSi2 was studied using synchrotron-radiation-based photoemission. In each, the Ni, Co, or Fe makes the largest contribution to the valence-band photoemission spectrum. The main nonbonding 3d Ni, Co, or Fe feature moves toward the Fermi level (EF) as Ni is replaced by Co or Fe. The presence of Ti increases the number of states near EF when compared to the Ni, Co, or Fe mono- and disilicides. The Si 2p core level becomes less symmetric and moves to lower binding energy when Ni substitutes for Co or Fe, suggesting that the Si 2p core hole is more effectively screened in Ti4Ni4Si7 than in the other ternary transition-metal silicides. © 1990 The American Physical Society.