New organic superconductor based on deuterated bis(ethylenedithio)-tetrathiafulvalene, κ-(d8-ET)4(HgBr2 . Hg2Br6)

Abstract

The deuterated organic salt based on (d8-ET) (ET is bis(ethylenedithio) tetrathiafulvalene (BEDT-TTF)) was synthesized with bromine-mercurate anion. X-ray crystallographic studies have demonstrated it to have the following formula, κ-(d8-ET)4 (HgBr2 . Hg2Br6). Various types of the temperature dependences of conductivity for the crystals from the same batch have been found but not one of the studied samples was a superconductor at ambient pressure. All crystals studied at ambient pressure seem to become superconductors at low pressure (~300 bar) with different Tc. Crystal structure features of this salt with d8-ET cation are compared with the structure of an organic superconductor (ET)4Hg2.89Br8 at ambient pressure. The differences in their superconducting properties are associated with high lability of Hg-containing salts