Férmions de Dirac e Weyl em NiTe_2

Abstract

At present, TMDs (Transition Metal Dichalcogenides) are of great interest in the field of condensed matter research. This interest is particularly relevant when it comes to materials where Dirac points can be observed. Although NiTe2 is an underexplored TMD, some of its characteristics are already known, such as superconductivity, planar Hall effect, negative magnetoresistance, and anisotropic transport. However, recent studies have not yet reported results regarding the presence or absence of Weyl semimetals. NiTe2 belongs to the 𝐷3𝑑 symmetry group and has inversion symmetry. One of its peculiar features is the presence of a Dirac node near the Fermi level. In this work, through the breaking of inversion symmetry, we will show that Weyl points emerge in the material. To achieve this, we broke the inversion symmetry by displacing the nickel atoms in the Z direction, which is equivalent to applying an electric field in this direction. With this displacement, the system begins to exhibit symmetries composed by the 𝐶3𝑣 group. With the natural breaking of inversion symmetry imposed by stacking, 14 pairs of Weyls were found in the first Brillouin zone.