Superconductivity in a New Family of Organic Conductors

Abstract

Evidence for superconductivity in ${(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{E})}_{4}$${(\mathrm{R}\mathrm{e}{\mathrm{O}}_{4})}_{2}$ [where BEDT-TTF is bis (ethylenedithiolo)tetrathiafulvalene] near 2 K for pressures above 4 kbar is reported. This is the first unambiguous observation of superconductivity in a sulfur-donor organic system. At higher pressures the transition temperature decreases rapidly, $\frac{d{T}_{c}}{\mathrm{dP}}\ensuremath{\sim}\ensuremath{-}0.3$ K/kbar. At low pressures this material exhibits a first-order metal-insulator transition, postulated to result from a change in the arrangement of the anions which are ordered at room temperature.