# Ru-doping on iron based pnictides: the "unfolded" dominant role of structural effects for superconductivity

## TL;DR

This study uses ab-initio calculations and an unfolding technique to analyze how Ru substitution affects the electronic structure and superconductivity in iron pnictides, emphasizing the dominant role of structural effects over impurity potential.

## Contribution

It demonstrates that local structural modifications, rather than impurity potential, primarily influence the electronic properties of Ru-doped iron pnictides, clarifying their role in superconductivity.

## Key findings

- Electronic properties agree with experiments, confirming short-range magnetic order.
- Fermi surfaces are more sensitive to structural parameters than impurity potential.
- Ru substitution mainly alters band structure through local structural changes.

## Abstract

We present an ab-initio study of Ru substitution in two different compounds, BaFe2As2 and LaFeAsO, pure and F-doped. Despite the many similarities among them, Ru substitution has very different effects on these compounds. By means of an unfolding technique, which allows us to trace back the electronic states into the primitive cell of the pure compounds, we are able to disentangle the effects brought by the local structural deformations and by the impurity potential to the states at the Fermi level. Our results are compared with available experiments and show: i) satisfying agreement of the calculated electronic properties with experiments, confirming the presence of a magnetic order on a short range scale; ii) Fermi surfaces strongly dependent on the internal structural parameters, more than on the impurity potential. These results enter a widely discussed field in the literature and provide a better understanding of the role of Ru in iron pnictides: although isovalent to Fe, the Ru-Fe substitution leads to changes in the band structure at the Fermi level mainly related to local structural modifications.