Superconductivity close to the charge-density-wave instability

¹  Regroupement Québécois sur le Matériaux de Pointe, Département de Physique, Université de Sherbrooke Sherbrooke, Québec, Canada, J1K-2R1
²  Canadian Insitute for Advanced Research - Toronto, Ontario, Canada

Corresponding author: cbourbon@physique.usherbrooke.ca

Received: 16 January 2010
Accepted: 6 April 2010

Abstract

We use the weak-coupling renormalization group method to examine the interplay between charge-density-wave and s-wave superconducting orders in a quasi–one-dimensional model of electrons interacting with acoustic phonons. The relative stability of both types of order is mapped out at arbitrary nesting deviations and Debye phonon frequency ω_D. We single out a power law increase of the superconducting T_c ~ ω_D^0.7 from a quantum critical point of charge-density-wave order triggered by nesting alterations. The results capture the key features shown by the proximity between the two types of ordering in the phase diagram of the recently discovered Perylene-based organic superconductor under pressure. The impact of Coulomb interaction on the relative stability of the competing phases is examined and discussed in connection with the occurrence of s-wave superconductivity in low-dimensional charge-density-wave materials.