Unconventional superconductivity and interaction induced Fermi surface reconstruction in the two-dimensional Edwards model

TL;DR

This study investigates how interactions in a two-dimensional Edwards model lead to Fermi surface reconstruction and unconventional superconductivity, revealing a transition from band renormalization to charge density wave formation and superconductivity with sign-changing order parameter.

Contribution

It demonstrates the emergence of a new Fermi surface and unconventional superconductivity induced by interaction-driven band renormalization in a general 2D transport model.

Findings

Fermi surface reconstruction occurs due to strong band renormalization.

Superconductivity with a sign-changing order parameter appears on new Fermi surface parts.

Charge density wave formation follows the emergence of the reconstructed Fermi surface.

Abstract

We study the competition between unconventional superconducting pairing and charge density wave (CDW) formation for the two-dimensional Edwards Hamiltonian at half filling, a very general two-dimensional transport model in which fermionic charge carriers couple to a correlated background medium. Using the projective renormalization method we find that a strong renormalization of the original fermionic band causes a new hole-like Fermi surface to emerge near the center of the Brillouin zone, before it eventually gives rise to the formation of a charge density wave. On the new, disconnected parts of the Fermi surface superconductivity is induced with a sign-changing order parameter. We discuss these findings in the light of recent experiments on iron-based oxypnictide superconductors.