Metal–Semiconductor Transition of the New Organic Conductor (DTEDT)₃Ag(CN)₂

Abstract

Crystal structure analysis, transport properties, and ESR study of the new organic conductor (DTEDT)₃Ag(CN)₂, where DTEDT is 2-(1,3-dithiol-2-ylidene)-5-(2-ethanediylidene-1,3-dithiole)-1,3,4,6-tetrathiapentalene, have been carried out. The crystal structure and the energy band structure of the present compound are the same as (DTEDT)₃Au(CN)₂, which shows superconductivity around 4 K at ambient pressure, whereas the electrical resistivity of the Ag(CN)₂ salt shows a metal–semiconductor transition at T_c = 40 K. The increase of the resistivity has been suppressed under a pressure of 10.3 kbar. The ESR spin susceptibility of this salt goes to zero below T_c without divergence of the linewidth. The ground state of (DTEDT)₃Ag(CN)₂ is a nonmagnetic semiconductor.