Abstract
Topological materials with band-crossing points exhibit interesting electronic characteristics and have special applications in electronic devices. However, to further facilitate the experimental detection of the signatures of these band crossings, topological materials with a large linear energy range around the band-crossing points need to be found, which is challenging. Here, via first-principle approaches, we report that the previously prepared P6/mmm-type CrB2 material is a topological metal with one pair of 1D band-crossing points, that is, nodal lines, in the kz = 0 plane, and one pair of 0D band-crossing points, that is, triple points, along the A–Γ–A’ paths. Remarkably, around these band-crossing points, a large linear energy range (larger than 1 eV) was found and the value was much larger than that found in previously studied materials with a similar linear crossing. The pair of nodal lines showed obvious surface states, which show promise for experimental detection. The effect of the spin–orbit coupling on the band-crossing points was examined and the gaps induced by spin–orbit coupling were found to be up to 69 meV. This material was shown to be phase stable in theory and was synthesized in experiments, and is therefore a potential material for use in investigating nodal lines and triple points.
Highlights
Topological semimetals/metals [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15], including nodal point semimetals/metals, nodal line semimetals/metals, and nodal surface semimetals/metals, with nontrivial band topologies, have attracted significant attention in the area of condensed matter physics
If the system is protected from proper crystal symmetry, the opposite chirality of the two Weyl points can coincide at a certain point, resulting in a Dirac point
We shall discuss the triply degenerate nodal point, P3, along the. These triply degenerate nodal points were formed by the crossing of a two-fold degenerated band and a non-degenerated band, which corresponded to the E1 and A1 irreducible representations, respectively, of the C6v symmetry
Summary
Topological semimetals/metals [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15], including nodal point semimetals/metals, nodal line semimetals/metals, and nodal surface semimetals/metals, with nontrivial band topologies, have attracted significant attention in the area of condensed matter physics. The investigation of nodal point semimetals/metals has not been limited to the cases of Weyl and Dirac nodal point materials [16,17,18,19,20] with two-fold and four-fold degenerated band crossings. By using first-principle approaches, we report a P6/mmm-type CrB2 topological metal with one pair of 1D band-crossing points, that is, 1D nodal lines, in the kz = 0 plane, and one pair of 0D band-crossing points, that is, triply degenerate points, along the A–Γ–A’ paths. The CrB2 topological metal is a good candidate for investigating the physical properties of nodal point and nodal line fermions, as well as the relationship between them
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