High-Pressure Study up to 9.9 GPa of Organic Mott Insulator, β′-(BEDT-TTF)₂AuCl₂

Abstract

We have investigated the resistivity of an organic Mott insulator, β′-(BEDT-TTF)₂AuCl₂, under extremely high pressures of up to 9.9 GPa, using the cubic anvil press, motivated by the fact that a related material, β′-(BEDT-TTF)₂ICl₂, shows the highest transition-temperature superconductivity among organics at 8.2 GPa. Through characterization by resistivity and susceptibility measurements at ambient pressure, we have confirmed that these two salts have common physical properties. Nevertheless, β′-(BEDT-TTF)₂AuCl₂ does not show superconductivity but remains semiconducting up to 9.9 GPa. We discuss the origin of these contrasting behaviors and suggest the cause to be the difference in anion size between the two salts.