Is Fermi-surface nesting the origin of superconductivity in iron pnictides?: A fluctuation-exchange-approximation study

TL;DR

This study investigates whether Fermi-surface nesting is responsible for high-temperature superconductivity in iron pnictides, finding that nesting alone is insufficient and local magnetic interactions may be key.

Contribution

It demonstrates through a fluctuation-exchange approximation that Fermi-surface nesting is not the sole driver of superconductivity in iron pnictides, highlighting the importance of local magnetic interactions.

Findings

Fermi-surface nesting does not necessarily lead to stripe antiferromagnetic order.

Superconductivity may involve local exchange interactions beyond Fermi-surface effects.

Fermi-surface nesting alone is insufficient to explain high-temperature superconductivity.

Abstract

We study whether Fermi-surface (FS) nesting can give rise to high-temperature superconductivity in iron pnictides. Starting with ab initio construction of an effective four-orbital model, we employ the fluctuation-exchange approximation to show that FS does not necessarily favor the stripe antiferromagnetic order observed in experiments, especially for realistic electronic correlations. If superconductivity in iron pnictides is magnetically mediated and has fully-gapped sign-reversing s-wave symmetry, our results suggest that the pairing interaction does not arise only from FS nesting and exchange interactions between local moments in the Fe 3d orbitals may play a crucial role.