Tight binding model for iron pnictides

TL;DR

This paper introduces a five-band tight-binding model for iron pnictides that accurately reproduces DFT band structures and explores how bond angle variations affect electronic properties.

Contribution

A novel tight-binding model with minimal parameters that captures key electronic features of iron pnictides and analyzes the impact of structural modifications.

Findings

Model reproduces DFT band structure with four parameters

Bond angle variations alter Fermi surface shape and orbital content

Model recovers known phenomenology of iron pnictides

Abstract

We propose a five-band tight-binding model for the Fe-As layers of iron pnictides with the hopping amplitudes calculated within the Slater-Koster framework. The band structure found in DFT, including the orbital content of the bands, is well reproduced using only four fitting parameters to determine all the hopping amplitudes. The model allows to study the changes in the electronic structure caused by a modification of the angle $\alpha$ formed by the Fe-As bonds and the Fe-plane and recovers the phenomenology previously discussed in the literature. We also find that changes in $\alpha$ modify the shape and orbital content of the Fermi surface sheets.