Anion disorder and two-dimensionality in the superconducting and SDW states of (TMTSF)2ClO4

The anion-disorder and two-dimensionality effect for the superconducting and SDW phase of (TMTSF)2ClO4 was investigated through static magnetization and resistance measurements for various cooling rates through the ClO4- anion ordering temperature. In the slowly cooled phase, the authors find a strong dependence of the superconducting transition temperature on the a-axis residual resistivity ρa due to the suppression of anion ordering. This behavior supports models of non-s-wave pairing in (TMTSF)2X. In the rapidly quenched phase, the transition temperature of SDW shows a large increase in the magnetic field. This means that the SDW phase of quenched (TMTSF)2ClO4 is strongly suppressed by the two-dimensionality of the system