Abstract. We propose a theoretical model of quasi–one-dimensional superconductors, with attractive electron-electron interactions dominant in the singlet d-wave channel and sub-dominant in the p-wave channel. We discuss, in the mean-field approximation, the effect of a magnetic field applied perpendicularly to the direction of the lowest conductivity. The lowest free energy phase corresponds to a singlet d-wave symmetry in low fields, but to a triplet symmetry in high fields. A first-order singlet-triplet phase transition is expected at moderate applied fields of a few teslas. We propose to ascribe the recent critical field and NMR experimental data, observed in superconducting (TMTSF)₂ClO₄ to such an effect.

PACS numbers: 74.70.Kn, 74.25.Op, 74.20.Rp

Print publication: Issue 3 (November 2007)
Received 1 August 2007, accepted for publication 4 September 2007
Published 28 September 2007