Abstract
Pressure-controlled switching between an insulating state and a superconducting state has been successfully realized on a supramolecular organic conductor θ-(DIETS)2[Au(CN)4] [DIETS = diiodo(ethylenedithio)diselenadithiafulvalene]. Strong contact between iodine on the donor (DIETS) molecule and nitrogen on the anion [Au(CN)4] genetates characteristic uniaxial strain effects on transport properties. Under the ambient pressure, the present system undergoes a semiconductor–insulator transition at 226 K. The effect of strains parallel to the conduction plane (ab-plane) is very small. Even under uniaxial strains up to 20 kbar along the a- and b-axis directions, the transition is not suppressed. Surprisingly, however, the c-axis strain induces a superconducting state with Tc of 8.6 K at 10 kbar. Band parameter calculation and the conductivity anisotropy ratio suggest that an increase in the bandwidth W associated with a c-axis strain transforms the system to the metallic and superconducting states. In the metallic state under c-axis strain, the temperature (T) dependence of the Hall coefficient (RH) and the Hall angle (θH) is expressed as RH∝T−1 and cotθH∝T2.
