Evolution of superconductivity in Fe-based systems with doping

TL;DR

This paper investigates how superconductivity evolves in iron-based materials as doping levels change, focusing on the symmetry and structure of the superconducting gap through theoretical analysis of pairing interactions.

Contribution

It introduces a simplified harmonic decomposition of pairing interactions to analyze the competition between s- and d-wave superconducting states in doped Fe-based systems.

Findings

Identification of dominant pairing symmetries in different doping regimes

Analysis of the competition between s- and d-wave solutions

Insights into superconductivity when only electron or hole pockets are present

Abstract

We study the symmetry and the structure of the gap in Fe-based superconductors by decomposing the pairing interaction obtained in the RPA into s- and d-wave components and into contributions from scattering between different Fermi surfaces. We show that each interaction is well approximated by the lowest angular harmonics and use this simplification to analyze the origin of the attraction in the two channels, the competition between s- and d-wave solutions, and the origin of superconductivity in heavily doped systems, when only electron or only hole pockets are present.