Electronic properties of TaAs₂ topological semimetal investigated by transport and ARPES

Abstract

We have performed electron transport and ARPES measurements on single crystals of transition metal dipnictide TaA$s_{2}$ 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 magnetic field and the [$\overline{2}$ 0 1] direction. The results indicate 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 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 investigating 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.

Electronic structure in a transition metal dipnictide TaAs2

“…Result of Laue diffraction to identify the orientation of the cleaved surface is presented in figure 2 and results of the ARPES measurements are presented in figures 3 and 4 to reveal the detailed electronic structure of TaAs 2 . The experimental Laue diffraction pattern is seen to match well with the QLaue simulation for the (201) plane, indicating that the favorable cleaving surface of TaAs 2 is the (201) surface, which also has the lowest cleavage energy [58]. This surface is different from the (010) surface that is predicted to host rotational crystalline-symmetry-protected surface states [17].…”

Evidence of linear and cubic Rashba effect in non-magnetic heterostructure

“…In the Γ 7 5 and Γ 7 6 levels, for k x ≲ 0.02 Å the linear RSO interaction strength is one order magnitude higher than the cubic type RSO with α R1 = 43 meVÅ and α R1 = 260 meVÅ. It is worthy to mention that in a recent study on TaAs 2 semimetal, the maximum spin splitting in Ta has been found to be 269 meV [52]. In this article, we have found that a larger splitting in Ta can be achieved by using oxide heterostructure of Ta-based material.…”

Correlation-Driven Topological Transition in Janus Two-Dimensional Vanadates

“…The values of the Hubbard parameter used for the d-orbitals of V are U = 4 eV for VSi 2 P 4 , and 2 eV for VSi 2 As 4 and VSiGeP 2 As 2 , and the Hund coupling J H is set at 0.87 eV. The main source of SOC in this compound is As; the value of SOC for As is estimated to be 0.164 eV [ 68 , 69 ].…”