Novel type of pairing in quasi-one-dimensional superconductivity

A new type of unconventional superconductivity develops in one-dimensional (1D) and quasi-one-dimensional (Q1D) metals mediated both by charge and spin fluctuations. The transition temperature T-c is higher for the singlet pairing than that for the triplet in general, but only by a few times. Therefore, the triplet pairing can be stabilized under moderately large Zeeman magnetic fields. The gap function inevitably changes its sign in the radial direction near the Fermi surface; especially in purely 1D case, the gap vanishes just at the Fermi points. The effect of the nonmagnetic impurity scattering in the unitarity limit is also considered. (C) 2002 Elsevier Science B.V. All rights reserved.