We investigate the electronic structure of the metallic ${\mathrm{NiS}}_{1-x}{\mathrm{Se}}_x$ system using various electron spectroscopic techniques. The band-structure results do not describe the details of the spectral features in the experimental spectrum, even for this paramagnetic metallic phase. However, a parametrized many-body multiband model is found to be successful in describing the Ni $2p$ core level and valence band, within the same model. The asymmetric line shape as well as the weak intensity feature in the Ni $2p$ core-level spectrum have been ascribed to extrinsic loss processes in the system. The presence of satellite features in the valence-band spectrum shows the existence of the lower Hubbard band, deep inside the $\mathrm{pd}$ metallic regime, consistent with the predictions of the dynamical mean-field theory.

• Received 7 October 1999

DOI:https://doi.org/10.1103/PhysRevB.61.16370