Charge–density-wave and superconductivity in the two-dimensional Little model

Abstract As a non-phonon mechanism of superconductivity (SC), Little has proposed models in which the pairing force is induced by electronic polarization of molecules embeded in the conductor. Hirsch and Scalapino have studied a tight-binding model of this type in one dimension (1D) and have found that superconductivity is dominated by charge–density-wave (CDW). We extend their calculations to two dimensions (2D). Our quantum Monte Carlo calculations suggest that the charge–density-wave formation is limited to a region close to half-filling. Outside of that superconductivity flourishes even in the presence of a finite onsite repulsion, demonstrating the Little model as a viable model for electronic mechanism of superconductivity. The results might be relevant to high-temperature superconductors.