The effect of spin fluctuations on the electronic structure in iron based superconductors

TL;DR

This paper investigates how spin fluctuations influence the electronic structure of iron-based superconductors, combining experimental data and theoretical calculations to predict observable effects in spectroscopic measurements.

Contribution

It provides a detailed theoretical analysis of spin fluctuation effects on electronic quasiparticles in iron pnictides, with predictions testable by ARPES and STS.

Findings

Reproduces quasiparticle dispersions consistent with experiments

Predicts signatures of spin fluctuations in spectroscopic data

Discusses the role of spin fluctuations in superconducting pairing

Abstract

Magnetic inelastic neutron scattering (INS) studies of iron-based superconductors reveal a strongly temperature-dependent spin-fluctuation spectrum in the normal conducting state, which develops a prominent low-energy resonance feature when entering the superconducting state. Angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy (STS) allow to study the fingerprints of fluctuation modes via their interactions with electronic quasiparticles. We calculate such fingerprints in 122 iron pnictides using an experimentally motivated spin-fluctuation spectrum and make a number of predictions that can be tested in ARPES and STS experiments. This includes discussions of the quasiparticle scattering rate and the superconducting order parameter. In quantitative agreement with experiment we reproduce the quasiparticle dispersions obtained from momentum distribution curves as well as energy distribution curves. We discuss the relevance of the coupling between spin fluctuations and electronic excitations for the superconducting mechanism.