What does d-wave symmetry tell us about the pairing mechanism?

TL;DR

This paper argues that d-wave symmetry in superconductors arises from repulsive interactions, with 2D effects and Coulomb wave vector structure playing key roles in stabilizing d_{x^2-y^2} pairing.

Contribution

It extends the Kohn-Luttinger theory to 2D lattices, highlighting the importance of wave vector structure in the Coulomb interaction for d-wave pairing.

Findings

D-wave symmetry results from repulsive interactions in 2D superconductors.

Van Hove singularities stabilize the d-wave state.

Wave vector structure of Coulomb interaction favors d_{x^2-y^2} pairing.

Abstract

In this paper we argue that d-wave symmetry is a general consequence of superconductivity driven by repulsive interactions. Van Hove (or flat band) effects, deriving from the two dimensionality of the $CuO_2$ plane are important in stabilizing this state. By extending the original Kohn-Luttinger picture to a 2 D lattice, we find that the screened Coulomb term has important wave vector structure which leads to $d_{x^2-y^2}$ superconductivity