Theoretical study on the anisotropic electronic structure of antiferromagnetic BaFe$_2$As$_2$ and Co-doped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ seen by angle-resolved photoemission

TL;DR

This theoretical study uses relativistic calculations to analyze the electronic anisotropy in antiferromagnetic BaFe$_2$As$_2$ and Co-doped variants, achieving good agreement with experimental ARPES spectra and tracking anisotropy evolution with doping.

Contribution

The paper provides a detailed theoretical analysis of in-plane electronic anisotropy in iron pnictides using one-step model calculations and alloy theory, directly comparing with experimental data.

Findings

Good agreement with experimental ARPES spectra.

The evolution of anisotropy with Co doping is nearly continuous.

Surface effects and termination signatures are identified.

Abstract

By means of one-step model calculations the strong in-plane anisotropy seen in angle-resolved photoemission of the well-known iron pnictide prototype compounds BaFe$_2$As$_2$ and Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ in their low-temperature antiferromagnetic phases is investigated. The fully-relativistic calculations are based on the Korringa-Kohn-Rostoker-Green function approach combined with the coherent potential approximation alloy theory to account for the disorder induced by Co substitution on Fe sites in a reliable way. The results of the calculations can be compared directly to experimental spectra of detwinned single crystals. One finds very good agreement with experiment and can reveal all features of the electronic structure contributing to the in-plane anisotropy. In particular the local density approximation can capture most of the correlation effects for the investigated system without the need for more advanced techniques. In addition, the evolution of the anisotropy for increasing Co concentration $x$ in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ can be tracked almost continuously. The results are also used to discuss surface effects and it is possible to identify clear signatures to conclude about different types of surface termination.