Pressure-induced suppression of the spin-gapped insulator phase in BaV S3: An infrared optical study

The metal-insulator transition in BaV S3 was studied at ambient pressure and under hydrostatic pressure up to p=26 kbar in the energy range of 2.5-500 meV. The charge gap determined from the optical reflectivity was enhanced, Δch (p) kB TMI (p) ≈12. This ratio is independent of pressure, indicating that the character of the transition did not vary along the p-T phase boundary. Above the critical pressure, pcr ∼20 kbar, metallic spectra were recorded in the whole temperature range, as expected from the shape of the phase diagram.