Multiband magnetism and superconductivity in Fe-based compounds

TL;DR

This paper explores the electronic, magnetic, and superconducting properties of Fe-based compounds, emphasizing the role of multiband Fermi surfaces and structural features in promoting high-temperature superconductivity.

Contribution

It introduces a model Hamiltonian for FeAs layers highlighting the importance of As atom puckering and multiband effects in Fe-based superconductors.

Findings

Identification of nesting-induced spin density-wave order in parent compounds

Linking high T_c superconductivity to multiband Fermi surface characteristics

Highlighting the role of As atom puckering in electron itinerancy

Abstract

Recent discovery of high T_c superconductivity in Fe-based compounds may have opened a new pathway to the room temperature superconductivity. The new materials feature FeAs layers instead of the signature CuO_2 planes of much-studied cuprates. A model Hamiltonian describing FeAs layers is introduced, highlighting the crucial role of puckering of As atoms in promoting d-electron itinerancy and warding off large local-moment magnetism of Fe ions, the main enemy of superconductivity. Quantum many-particle effects in charge, spin and multiband channels are explored and a nesting-induced spin density-wave order is found in the parent compund. We argue that this largely itinerant antiferromagnetism and high T_c itself are essentially tied to the multiband nature of the Fermi surface.