Symmetry-enforced band crossings in trigonal materials: Accordion states and Weyl nodal lines
Abstract
Nonsymmorphic symmetries, such as screw rotations or glide reflections, can enforce band crossings within high-symmetry lines or planes of the Brillouin zone. When these band degeneracies are close to the Fermi energy, they can give rise to a number of unusual phenomena, e.g., anomalous magnetoelectric responses, transverse Hall currents, and exotic surface states. In this paper, we present a comprehensive classification of such nonsymmorphic band crossings in trigonal materials with strong spin-orbit coupling. We find that in trigonal systems there are two different types of nonsymmorphic band degeneracies: (i) Weyl points protected by screw rotations with an accordion-like dispersion, and (ii) Weyl nodal lines protected by glide reflections. We report a number of existing materials, where these band crossings are realized near the Fermi energy. This includes Cu2SrSnS4 and elemental tellurium (Te), which exhibit accordion Weyl points, and the tellurium-silicon clathrate Te16Si38 , which shows Weyl nodal lines. The ab initio band structures and surface states of these materials are studied in detail, and implications for experiments are briefly discussed.
- Publication:
-
Physical Review Materials
- Pub Date:
- December 2019
- DOI:
- 10.1103/PhysRevMaterials.3.124204
- arXiv:
- arXiv:1908.00901
- Bibcode:
- 2019PhRvM...3l4204C
- Keywords:
-
- Condensed Matter - Materials Science;
- Condensed Matter - Mesoscale and Nanoscale Physics
- E-Print:
- 13 pages, 11 figures, 4 tables