Superconducting pairing and density-wave instabilities in quasi-one-dimensional conductors

Abstract

Using a renormalization group approach, we determine the phase diagram of an extended quasi-one-dimensional electron gas model that includes interchain hopping, nesting deviations, and both intrachain and interchain repulsive interactions. d-wave superconductivity, which dominates over the spin-density-wave (SDW) phase at large nesting deviations, becomes unstable to the benefit of a triplet f-wave phase for a weak repulsive interchain backscattering term g1⊥>0, despite the persistence of dominant SDW correlations in the normal state. Antiferromagnetism becomes unstable against the formation of a charge-density-wave state when g1⊥ exceeds some critical value. While these features persist when both Umklapp processes and interchain forward scattering (g2⊥) are taken into account, the effect of g2⊥ alone is found to frustrate nearest-neighbor interchain d- and f-wave pairing and instead favor next-nearest-neighbor interchain singlet or triplet pairing. We argue that the close proximity of SDW and charge-density-wave phases, singlet d-wave, and triplet f-wave superconducting phases in the theoretical phase diagram provides a possible explanation for recent puzzling experimental findings in the Bechgaard salts, including the coexistence of SDW and charge-density-wave phases and the possibility of a triplet pairing in the superconducting phase.

Source-reported materials — not catalogue approval

Similar papers