Effect of doping on the magnetostructural ordered phase of iron arsenides: A comparative study of the resistivity anisotropy in the doped BaFe$_2$As$_2$ with doping into three different sites

TL;DR

This study compares how doping at different lattice sites affects resistivity anisotropy and magnetic ordering in BaFe$_2$As$_2$ superconductors, revealing impurity scattering as a key factor in the antiferromagnetic/orthorhombic phase.

Contribution

It demonstrates that doping introduces disorder influencing resistivity anisotropy and magnetic transition suppression, highlighting site-dependent effects in iron arsenide superconductors.

Findings

Resistivity anisotropy correlates with residual resistivity.

Doping-induced disorder controls the suppression of AFO transition temperature.

Impurity scattering from dopants causes resistivity anisotropy in the AFO phase.

Abstract

In order to unravel a role of doping in the iron-based superconductors, we investigated the in-plane resistivity for BaFe$_2$As$_2$ doped at either of the three different lattice sites, Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, BaFe$_2$(As$_{1-x}$P$_x$)$_2$, and Ba$_{1-x}$K$_x$Fe$_2$As$_2$, focusing on the doping effect in the low-temperature antiferromagnetic/orthorhombic (AFO) phase. A major role of doping in the high-temperature paramagnetic/tetragonal (PT) phase is known to change the Fermi surface by supplying charge carriers or by exerting chemical pressure. In the AFO phase, we found a clear correlation between the magnitude of residual resistivity and resistivity anisotropy. This indicates that the resistivity anisotropy originates from the anisotropic impurity scattering from dopant atoms. The magnitude of residual resistivity is also found to be a parameter controlling the suppression rate of AFO ordering temperature $T_s$. Therefore, the dominant role of doping in the AFO phase is to introduce disorder to the system, distinct from that in the PT phase.