In-plane electronic anisotropy in the antiferromagnetic-orthorhombic phase of isovalent-substituted Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$

TL;DR

This study investigates in-plane resistivity anisotropy and electronic structure in Ru-substituted BaFe$_2$As$_2$, revealing impurity scattering as the main cause of anisotropy rather than band structure changes.

Contribution

It provides new insights into the origin of resistivity anisotropy, showing that impurity scattering dominates over band structure effects in Ru-doped BaFe$_2$As$_2$.

Findings

Resistivity anisotropy increases with Ru doping but is smaller than Co doping.

Electronic structure remains nearly isotropic between parent and Ru-doped compounds.

Impurity scattering, not band structure, causes resistivity anisotropy.

Abstract

We have studied the anisotropy in the in-plane resistivity and the electronic structure of isovalent Ru-substituted BaFe$_2$As$_2$ in the antiferromagnetic-orthorhombic phase using well-annealed crystals. The anisotropy in the residual resistivity component increases in proportional to the Ru dopant concentration, as in the case of Co-doped compounds. On the other hand, both the residual resistivity and the resistivity anisotropy induced by isovalent Ru substitution is found to be one order of magnitude smaller than those induced by heterovalent Co substitution. Combined with angle-resolved photoemission spectroscopy results, which show almost the same anisotropic band structure both for the parent and Ru-substituted compounds, we confirm the scenario that the anisotropy in the residual resistivity arises from anisotropic impurity scattering in the magneto-structurally ordered phase rather than directly from the anisotropic band structure of that phase.