Fermiology, Orbital Order, Orbital Fluctuation and Cooper Pairing in Iron-based Superconductors

TL;DR

This paper investigates the reasons behind the high critical temperatures in certain iron-based superconductors with only electron pockets and explores how orbital order and fluctuations influence Cooper pairing mechanisms.

Contribution

It provides new insights into the role of orbital phenomena and electronic structure in enhancing superconductivity in iron-based materials.

Findings

High T_c explained by specific electronic structures

Orbital fluctuations significantly affect pairing mechanisms

Orbital order impacts superconducting properties

Abstract

We address two important issues that arise in recent studies of iron-based superconductivity. (1) Why are the T_c of A_xFe_{2-y}Se_2 and the single unit cell FeSe on SrTiO$_3$ so high despite both only have electron pockets? (2) What (if any) are the effects of orbital order and orbital fluctuation on the Cooper pairing. Our conclusions are summarized in the third paragraph of the paper.