Regensburg 2022 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 25: Topological Semimetals
TT 25.7: Vortrag
Donnerstag, 8. September 2022, 11:30–11:45, H3
Network of topological nodal planes, multifold degeneracies, and Weyl points in CoSi — •Nico Huber1, Kirill Alpin2, Andreas P. Schnyder2, Christian Pfleiderer1, and Marc A. Wilde1 — 1TU Munich — 2MPI for Solid State Research, Stuttgart
The discovery of multifold-fermions [1,2] and symmetry-enforced topological band crossings that are generically located at the Fermi level [3] has recently generated tremendous interest. However, the putative relationship between all topological charges remained unexplored up to now. We report the experimental identification of symmetry-enforced nodal planes (NPs) in CoSi which together with point degeneracies form a network of topological band crossings. In our study [4] we combined measurements of Shubnikov-de Haas (SdH) oscillations with first-principle electronic structure calculations, a symmetry analysis of SG 198, as well as a direct calculation of the topological charges. The observation of two nearly dispersionless SdH frequency branches is shown to provide clear evidence of four Fermi surface sheets around the R point and their pairwise degeneracy at the NPs on the Brillouin zone boundary. Our results further show that the crystalline symmetry enforces a topological charge of the NPs. Taken together, the comprehensive identification of all topological band crossings in the electronic structure of CoSi we report represents a showcase of an entire network of interconnected topological charges.
[1] Rao et al., Nature 567, 496 (2019)
[2] Sanchez et al., Nature 567, 500 (2019)
[3] Wilde et al., Nature 594, 374 (2021)
[4] Huber et al., arXiv:2107.02820 (accepted in PRL) (2022)