The pressure-temperature phase diagram of the organic superconductor $(\mathrm{TMTSF}{)}_2{\mathrm{FSO}}_3$ is refined by performing measurements of the interlayer resistance ${(R}_{\mathrm{zz}})$ and the longitudinal thermoelectric power ${(S}_{\mathrm{xx}}).\mathrm{}$ In addition to refining the phase transitions previously discussed in the literature, the results show at least two new phase changes at high pressure. The complexity of the phase diagram suggests that the finite electric dipole moment of the asymmetric ${\mathrm{FSO}}_3$ anions, which gives these anions an additional degree of freedom, should be taken into account in addition to their structural ordering.

• Received 28 June 2002

DOI:https://doi.org/10.1103/PhysRevB.67.014516