Metal-insulator transition in NiS2-x Sex

Abstract

The origin of the gap in NiS2 as well as the pressure- and doping-induced metal-insulator transition in the NiS2-x Sex solid solutions are investigated both theoretically using the first-principles band structures combined with the dynamical mean-field approximation for the electronic correlations and experimentally by means of infrared and x-ray absorption spectroscopies. The bonding-antibonding splitting in the S-S (Se-Se) dimer is identified as the main parameter controlling the size of the charge gap. The implications for the metal-insulator transition driven by pressure and Se doping are discussed. © 2010 The American Physical Society.