Suppression of backward scattering of Dirac fermions in iron pnictides Ba(Fe$_{1-x}$Ru$_x$As)$_2$

TL;DR

This study demonstrates that Dirac fermions in Ba(Fe$_{1-x}$Ru$_x$As)$_2$ are resilient to impurity scattering from Ru substitution, maintaining their transport properties despite lattice distortions affecting other bands.

Contribution

It reveals the robustness of Dirac cone electronic transport against impurity scattering in iron pnictides with Ru substitution, highlighting their unique linear dispersion characteristics.

Findings

Dirac fermions' transport remains unaffected by Ru impurities.

Inverse mobility scales with the square root of carrier number.

Scattering effects are analyzed via mean free path estimates.

Abstract

We report electronic transport of Dirac cones when Fe is replaced by Ru, which has an isoelectronic electron configuration to Fe, using single crystals of Ba(Fe$_{1-x}$Ru$_x$As)$_2$. The electronic transport of parabolic bands is shown to be suppressed by scattering due to the crystal lattice distortion and the impurity effect of Ru, while that of the Dirac cone is not significantly reduced due to the intrinsic character of Dirac cones. It is clearly shown from magnetoresistance and Hall coefficient measurements that the inverse of average mobility, proportional to cyclotron effective mass, develops as the square root of the carrier number (n) of the Dirac cones. This is the unique character of the Dirac cone linear dispersion relationship. Scattering of Ru on the Dirac cones is discussed in terms of the estimated mean free path using experimental parameters.