Reversed anisotropy of the in-plane resistivity in the antiferromagnetic phase of iron tellurides

TL;DR

This study reveals that impurity-induced resistivity anisotropy in iron tellurides exhibits reversed sign compared to iron arsenides, indicating a universal impurity scattering effect in the magneto-structurally ordered phase of iron-based materials.

Contribution

It demonstrates the impurity-dependent resistivity anisotropy in iron tellurides and suggests a universal impurity scattering mechanism across iron-based superconductors.

Findings

Resistivity anisotropy is opposite in sign to iron arsenides.

Magnitude of anisotropy correlates with impurity amount.

Impurity scattering is a key factor in anisotropic transport.

Abstract

We systematically investigated the anisotropic in-plane resistivity of the iron telluride including three kinds of impurity atoms: excess Fe, Se substituted for Te, and Cu substituted for Fe. Sizable resistivity anisotropy was found in the magneto-structurally ordered phase whereas the sign is opposite ($\rho_a$ $>$ $\rho_b$, where the $b$-axis parameter is shorter than the $a$-axis one) to that observed in the transition-metal doped iron arsenides ($\rho_a$ $<$ $\rho_b$). On the other hand, our results demonstrate that the magnitude of the resistivity anisotropy in the iron tellurides is correlated with the amount of impurities, implying that the resistivity anisotropy originates from an exotic impurity effect like that in the iron arsenides. This suggests that the anisotropic carrier scattering by impurities is a universal phenomenon in the magneto-structurally ordered phase of the iron-based materials.