Effect of radiation damage on the metal-insulator transition and low-temperature transport in the tetramethyltetraselenofulvalinium PF6 salt [(TMTSF)2PF6]

We have measured the resistance, magnetoresistance, and nonlinear conductivity in a series of tetramethyltetraselenofulvalinium phosphorus hexafluoride [(TMTSF)2PF6] crystals which have been damaged with 2.5-MeV protons. For radiation dosages which correspond to 400-ppm damage we find that the effects of the damage may be simply related to an increased scattering rate in the low-temperature transport. However, even with such low values of damage the metal-insulator transition at ambient pressure is smeared and shifted to lower temperature while the superconducting transition at 11 kbar is suppressed to less than our measuring temperature of 20 mK by 100 ppm. At 1000 ppm the spin-density-wave transition is suppressed. © 1982 The American Physical Society.