VALENCE-BAND ELECTRONIC-STRUCTURE OF NISI2 AND COSI2 - EVIDENCE OF THE SI S-ELECTRONIC STATE AT THE FERMI EDGE

It is found that the Si L2,3 soft-x-ray emission band of a NiSi2 single crystal has two main peaks at h91 and 100 eV, where the Si L2,3 spectrum is expected to reflect the density of states of the valence band with s and d symmetry. The sharp peaks at the top of the valence band are concluded to be due to the s band that mainly originated from the Si s state and are not due to the d band that originated from the Ni d state, which is a clear departure from the existing widely accepted explanation of the valence-band density of states. A similar result may be true for CoSi2. © 1990 The American Physical Society.