Mixed-State Effect on the Low-Energy Spin Dynamics in Optimally-doped Iron Pnictide Superconductors

TL;DR

This study investigates how magnetic fields influence low-energy spin dynamics in optimally-doped iron pnictide superconductors, using a phenomenological model to differentiate between $s_{}$ and s-wave pairing symmetries through neutron scattering data.

Contribution

It introduces a model-based analysis of mixed-state effects on spin dynamics, proposing a method to distinguish pairing symmetries in iron pnictide superconductors.

Findings

Spin susceptibility results align with neutron scattering experiments.

Field-induced intensity changes differ between $s_{}$ and s-wave symmetries.

Proposes a way to identify pairing symmetry via magnetic field effects.

Abstract

Based on a phenomenological model with $s_{\pm}$ or s-wave pairing symmetry, the mixed-state effect on the low-energy spin dynamics in optimally-doped iron pnictide superconductors is studied by solving Bogoliubov-de Gennes equations. Our results of the spin susceptibility at $\mathbf{q}=\mathbf{Q}$ in the normal, superconducting and mixed states agree qualitatively with recent neutron scattering experiments. We also propose that the field-induced intensity change shows different behaviors between the $s_{\pm}$ and s-wave symmetries in both momentum and real space, thus it can be used to distinguish these two pairing symmetries.