Electronic Structure of NiS 1 − x Se x across the Phase Transition

We report very highly resolved photoemission spectra of ${\mathrm{NiS}}_{1\ensuremath{-}x}{\mathrm{Se}}_{x}$ across the so-called metal-insulator transition as a function of temperature as well as composition. The present results convincingly demonstrate that the low temperature, antiferromagnetic phase is metallic, with a reduced density of states at ${E}_{F}$. This decrease is due possibly to the opening of gaps along specific directions in the Brillouin zone caused by the antiferromagnetic ordering.