Network of topological nodal planes, multifold degeneracies, and Weyl points in CoSi

We report the identification of symmetry-enforced nodal planes (NPs) in CoSi providing the missing topological charges in an entire network of band-crossings comprising in addition multifold degeneracies and Weyl points, such that the fermion doubling theorem is satisfied. In our study we have combi...

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Bibliographic Details
Published in:arXiv.org 2021-07
Main Authors: Huber, Nico, Alpin, Kirill, Causer, Grace L, Worch, Lukas, Bauer, Andreas, Benka, Georg, Hirschmann, Moritz M, Schnyder, Andreas P, Pfleiderer, Christian, Wilde, Marc A
Format: Article
Language:English
Subjects:
Electronic structure
Fermi surfaces
Fermions
Orthogonality
Spin-orbit interactions
Symmetry
Topology
Wave functions
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Summary:We report the identification of symmetry-enforced nodal planes (NPs) in CoSi providing the missing topological charges in an entire network of band-crossings comprising in addition multifold degeneracies and Weyl points, such that the fermion doubling theorem is satisfied. In our study we have combined measurements of Shubnikov-de Haas (SdH) oscillations in CoSi with material-specific calculations of the electronic structure and Berry curvature, as well as a general analysis of the band topology of space group (SG) 198. The observation of two nearly dispersionless SdH frequency branches provides unambiguous evidence of four Fermi surface sheets at the R point that reflect the symmetry-enforced orthogonality of the underlying wave functions at the intersections with the NPs. Hence, irrespective of the spin-orbit coupling strength, SG198 features always six- and fourfold degenerate crossings at R and \(\Gamma\) that are intimately connected to the topological charges distributed across the network.
ISSN:2331-8422
DOI:10.48550/arxiv.2107.02820