Electronic Structure of Prototype AFe_2As_2 and ReOFeAs High-Temperature Superconductors: a Comparison

TL;DR

This study compares the electronic structures of AFe_2As_2 and ReOFeAs high-temperature superconductors, revealing similar densities of states and Fermi surfaces, suggesting AFe_2As_2 as a simpler model for understanding superconductivity in FeAs compounds.

Contribution

It provides a detailed ab initio comparison showing that AFe_2As_2 and ReOFeAs have nearly identical electronic spectra, highlighting AFe_2As_2 as a generic system for studying FeAs-based superconductivity.

Findings

Similar densities of states around the Fermi level

Almost identical Fermi surfaces for both compounds

Electronic spectra dominated by Fe d-orbitals

Abstract

We have performed ab initio LDA calculations of electronic structure of newly discovered prototype high-temperature superconductors AFe_2As_2 (A=Ba,Sr) and compared it with previously calculated electronic spectra of ReOFeAs (Re=La,Ce,Pr,Nd,Sm). In all cases we obtain almost identical densities of states in rather wide energy interval (up to 1 eV) around the Fermi level. Energy dispersions are also very similar and almost two-dimensional in this energy interval, leading to the same basic (minimal) model of electronic spectra, determined mainly by Fe d-orbitals of FeAs layers. The other constituents, such as A ions or rare earths Re (or oxygen states) are more or less irrelevant for superconductivity. LDA Fermi surfaces for AFe_2As_2 are also very similar to that of ReOFeAs. This makes the more simple AFe_2As_2 a generic system to study high-temperature superconductivity in FeAs - layered compounds.