Pseudogap in cuprate and organic superconductors

TL;DR

This paper investigates the pseudogap phenomenon in cuprate and organic superconductors using the dynamical cluster approximation, revealing how increasing Coulomb interaction leads to pseudogap formation through cluster-bath state destruction.

Contribution

It demonstrates the mechanism of pseudogap formation via cluster-bath state destruction and explains its momentum dependence without confirming preformed pairs.

Findings

Pseudogap arises from destruction of Kondo states in clusters.

Pseudogap appears first at anti-nodal points due to weaker bath coupling.

Pseudogap can be interpreted as preformed d-wave pairs, but not conclusively proven.

Abstract

We study the pseudogap present in cuprate and organic superconductors. We use the dynamical cluster approximation (DCA), treating a cluster embedded in a bath. As the Coulomb interaction is increased, cluster-bath Kondo states are destroyed and bound cluster states formed. We show that this leads to a pseudogap. Due to weaker coupling to the bath for the anti-nodal point, this happens first for this point, explaining the k-dependence of the pseudogap. The pseudogap can be understood in terms of preformed d-wave pairs, but it does not prove the existence of such pairs.