Pressure and alloying effects on the metal to insulator transition in NiS2-xSex studied by infrared spectroscopy
Abstract
The metal to insulator transition in the charge transfer NiS2-xSex compound has been investigated through infrared reflectivity. Measurements performed by applying pressure to pure NiS2 (lattice contraction) and by Se-alloying (lattice expansion) reveal that in both cases an anomalous metallic state is obtained. We find that optical results are not compatible with the linear Se-alloying vs Pressure scaling relation previously established through transport, thus pointing out the substantially different microscopic origin of the two transitions.
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