Spin fluctuations in iron pnictides and chalcogenides: From antiferromagnetism to superconductivity

TL;DR

This review summarizes recent neutron scattering studies on spin dynamics in iron-based superconductors, highlighting magnetic resonances, spin anisotropy, and their implications for understanding superconductivity.

Contribution

It provides a comprehensive overview of recent experimental findings on spin fluctuations, including magnetic resonant modes and spin anisotropy, advancing understanding of their role in superconductivity.

Findings

Observation of magnetic resonant modes in new superconductors

Detection of spin anisotropy across various compositions

Identification of momentum-space anisotropy linked to spin-nematic order

Abstract

The present article reviews recent experimental investigations of spin dynamics in iron-based superconductors and their parent compounds by means of inelastic neutron scattering. It mainly focuses on the most contemporary developments in this field, pertaining to the observations of magnetic resonant modes in new superconductors, spin anisotropy of low-energy magnetic fluctuations that has now been observed in a wide range of chemical compositions and doping levels, as well as their momentum-space anisotropy incurred by the spin-nematic order. The implications of these new findings for our understanding of the superconducting state, along with the remaining unsettled challenges for neutron spectroscopy, are discussed.