A minimal two-band model for the superconducting Fe-pnictides

TL;DR

This paper introduces a simplified two-band model that captures the key electronic and magnetic properties of Fe-pnictide superconductors, aiding understanding of their low-energy physics.

Contribution

The paper presents a minimal two-band model that reproduces the Fermi surface topology and magnetic fluctuations of Fe-pnictides, highlighting the essential low-energy physics.

Findings

Model reproduces Fermi surface topology

Captures ferromagnetic and SDW fluctuations

Contains essential low-energy physics

Abstract

Following the discovery of the Fe-pnictide superconductors, LDA band structure calculations showed that the dominant contributions to the spectral weight near the Fermi energy came from the Fe 3d orbitals. The Fermi surface is characterized by two hole surfaces around the $\Gamma$ point and two electron surfaces around the M point of the 2 Fe/cell Brillouin zone. Here, we describe a 2-band model that reproduces the topology of the LDA Fermi surface and exhibits both ferromagnetic and $q=(\pi,0)$ spin density wave (SDW) fluctuations. We argue that this minimal model contains the essential low energy physics of these materials.