Ultra high pressure application to organic conductors

Under pressures as high as 20 GPa at room temperature the electronic and structural properties of organic conductors were measured to search for interesting pressure regimes where novel electronic states were expected. Thermopower, two-probe electrical resistance and contraction of sample’s volume were measured on the organic conductors: ϑ-(BEDT-TTF)2CsZn(SCN)4, α-(BEDT-TTF)2I3, (BEDT-TTF)2PF6 and (BEDT-TTF)-TCNQ. All the materials exhibited a positive thermopower of the order of 10 µV/K. At about 4–7 GPa (crossover pressure Px) sharp changes were found in the pressure dependence of electronic and mechanical properties of all the substances under consideration related probably to the structural changes under pressure.