Neutron Scattering Resonance and the Fe-pnictide Superconducting Gap

TL;DR

This paper investigates neutron scattering resonances in Fe-pnictide superconductors, showing that different gap structures can produce similar resonance features, and suggests momentum transfer analysis can help distinguish them.

Contribution

It provides a theoretical analysis of neutron scattering resonances in Fe-pnictides using a five orbital model, exploring how different gap symmetries affect the resonance.

Findings

Both sign-switched and extended s-wave gaps fit current data for q* near (π, 0)

Scattering at different momentum transfers can differentiate gap structures

The model aligns with experimental observations of neutron resonance

Abstract

The existence of a neutron scattering resonance at a wavevector q* implies a sign change of the gap between two Fermi surface regions separated by wavevector q* . For the Fe pnictides, a resonance has been observed for a wavevector q* which connects a hole Fermi surface around the $\Gamma$ point with an electron Fermi surface around the X or Y points of the 1 Fe/unit cell Brillouin zone. Here we study the neutron scattering resonance for a five orbital model within an RPA-BCS approximation. Our results show that both sign-switched and extended s-wave gaps are consistent with the present data for q* near ($\pi$, 0) and that scattering at other momentum transfers can be useful in distinguishing between gap structures.