Does long-range antiferromagnetism help or inhibit superconductivity?

TL;DR

This paper investigates whether long-range antiferromagnetism promotes or suppresses superconductivity in a Hubbard model, concluding that strong Coulomb repulsion prevents coexistence of both states.

Contribution

It provides a detailed analysis of the interplay between antiferromagnetism and superconductivity, showing that large Coulomb repulsion inhibits their coexistence.

Findings

Triplet pairs with d-wave symmetry contribute to the suppression.

Long-range antiferromagnetism does not support coexistence with superconductivity at high Coulomb U.

Spin-density wave fluctuations do not alter the main conclusion.

Abstract

We analyze the possible existence of a superconducting state in a background with long-range antiferromagnetism. We consider a generalized Hubbard model with nearest-neighbor correlated hopping in a square lattice. Near half filling, the model exhibits a d-wave-Bardeen-Cooper-Schrieffer (BCS) solution in the paramagnetic state. The superconducting solution would be enhanced by the antiferromagnetic background if the contribution of triplet pairs with d-wave symmetry and total momentum (pi, pi) could be neglected. However, we find that due to their contribution, the coexistence of superconductivity and long-range antiferromagnetism is ruled out for large values of the Coulomb repulsion U. Spin-density wave fluctuations (SDWF) do not change this result.