Electronic properties of TaAs2 topological semimetal investigated by transport and ARPES

TL;DR

This study combines transport measurements, ARPES, and first-principles calculations to explore the electronic structure of TaAs2, revealing elliptical Fermi surfaces, multiple carrier types, and the potential for investigating Dirac and Weyl physics.

Contribution

It provides a comprehensive experimental and theoretical analysis of TaAs2's electronic properties, highlighting its suitability for studying topological Dirac and Weyl points.

Findings

Elliptical Fermi surface cross-sections identified.

At least four types of charge carriers detected.

Fermi level shifted closer to Dirac points due to n-doping.

Abstract

We have performed electron transport and ARPES measurements on single crystals of transition metal dipnictide TaAs2 cleaved along the ($\overline{2}$ 0 1) surface which has the lowest cleavage energy. A Fourier transform of the Shubnikov-de Haas oscillations shows four different peaks whose angular dependence was studied with respect to the angle between the magnetic field and the [$\overline{2}$ 0 1] direction. The results indicate the elliptical shape of the Fermi surface cross-sections. Additionally, a mobility spectrum analysis was carried out, which also reveals at least four types of carriers contributing to the conductance (two kinds of electrons and two kinds of holes). ARPES spectra were taken on freshly cleaved ($\overline{2}$ 0 1) surface and it was found that bulk states pockets at the constant energy surface are elliptical, which confirms the magnetotransport angle dependent studies. First-principles calculations support the interpretation of the experimental results. The theoretical calculations better reproduce the ARPES data if the theoretical Fermi level is increased, which is due to a small n-doping of the samples. This shifts the Fermi level closer to the Dirac point, allowing to investigate the physics of the Dirac and Weyl points, making this compound a platform for the investigation of the Dirac and Weyl points in three-dimensional materials.