Pressure-induced metallic resistivity of PF6− doped poly(3-methylthiophene)

Electrical resistivity of poly(3-methylthiophene) doped with PF6− has been studied under pressure up to 13 kbar using a self-clamped beryllium-copper pressure cell. Application of the pressure induces a metallic temperature dependence in resistivity at low temperatures. Below about 4 K, T12 dependence in electrical conductivity was observed, which can be explained taking the electron-electron interaction in a disordered system into account. We show that the extended heterogeneous model by Kaiser and Graham gives a good fit to the temperature dependence of the conductivity at low temperatures in the whole range of the pressure applied.