Electronic Structure, Magnetism and Superconductivity of Layered Iron Compounds

TL;DR

This paper reviews the electronic structure, magnetism, and superconductivity in layered iron compounds, highlighting their similar Fermi surfaces, magnetic properties, and the role of spin fluctuations in superconductivity.

Contribution

It provides a comparative analysis of electronic structures across four families of iron-based superconductors, emphasizing the importance of itinerant magnetism and proposing a nematic phase in the phase diagram.

Findings

Fermi surface consists of disconnected hole and electron cylinders

Strong evidence for itinerant spin fluctuations related to superconductivity

Proposed nematic phase between structural and SDW transitions

Abstract

The layered iron superconductors are discussed using electronic structure calculations. The four families of compounds discovered so far, including Fe(Se,Te) have closely related electronic structures. The Fermi surface consists of disconnected hole and electron cylinders and additional hole sections that depend on the specific material. This places the materials in proximity to itinerant magnetism, both due to the high density of states and due to nesting. Comparison of density functional results and experiment provides strong evidence for itinerant spin fluctuations, which are discussed in relation to superconductivity. It is proposed that the intermediate phase between the structural transition and the SDW transition in the oxy-pnictides is a nematic phase.