Resonant impurity states in chemically disordered half-Heusler Dirac semimetals

TL;DR

This study investigates electron transport in disordered half-Heusler Dirac semimetals, revealing impurity-induced resonant states at the Dirac point and significant spin Hall effects, with implications for spintronics.

Contribution

First-principles CPA calculations uncover impurity resonant levels at the Dirac point and analyze their impact on conductivity and spin Hall effects in disordered half-Heusler alloys.

Findings

Impurity resonant levels are present at the Dirac point.

Residual conductivity is suppressed by impurity scattering.

Large spin Hall conductivity leads to high spin Hall angles.

Abstract

We address the electron transport characteristics in bulk half-Heusler alloys with their compositions tuned to the borderline between topologically nontrivial semi-metallic and trivial semiconducting phases. The precise first-principles calculations based on the coherent potential approximation (CPA) reveal that all the studied systems exhibit sets of dispersionless impurity-like resonant levels, with one of them being located right at the Dirac point. By means of the Kubo formalism we reveal that the residual conductivity of these alloys is strongly suppressed by impurity scattering, whereas the spin Hall conductivity exhibits a large value which is comparable to that of Pt, thereby leading to divergent spin Hall angles.