Superconductivity in Iron Compounds

TL;DR

This review discusses the discovery, properties, and ongoing research challenges of iron-based superconductors, highlighting their complex behaviors, relationships with magnetism, and the quest to understand their high critical temperatures.

Contribution

It provides a comprehensive overview of iron-based superconductors, consolidating diverse data and insights into their superconductivity and material properties.

Findings

Superconductivity up to 56 K in various Fe-based compounds

Complex interplay between magnetism and superconductivity

Sample quality impacts understanding of nodal structures

Abstract

Kamihara and coworkers' report of superconductivity at Tc = 26 K in fluorine-doped LaFeAsO inspired a worldwide effort to understand the nature of the superconductivity in this new class of compounds. These iron pnictide and chalcogenide (FePn/Ch) superconductors have Fe electrons at the Fermi surface, plus an unusual Fermiology that can change rapidly with doping, which lead to normal and superconducting state properties very different from those in standard electron-phonon coupled 'conventional' superconductors. Clearly superconductivity and magnetism/magnetic fluctuations are intimately related in the FePn/Ch - and even coexist in some. Open questions, including the superconducting nodal structure in a number of compounds, abound and are often dependent on improved sample quality for their solution. With Tc values up to 56 K, the six distinct Fe-containing superconducting structures exhibit complex but often comparable behaviors. The search for correlations and explanations in this fascinating field of research would benefit from an organization of the large, seemingly disparate data set. This review attempts to provide an overview, using numerous references, with a focus on the materials and their superconductivity.