Berlin 2024 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 57: Topology: Poster
TT 57.4: Poster
Mittwoch, 20. März 2024, 15:00–18:00, Poster E
Band structure and topology of the chiral semimetal CoSi — •B.V. Schwarze1,2, J. Hornung1, K. Manna3, S. Shekhar3, S. Chattopadhyay1, C. Felser3, and J. Wosnitza1,2 — 1Hochfeld-Magnetlabor Dresden (HLD-EMFL), HZDR, Dresden, Germany — 2Institut für Festkörper- und Materialphysik, TU Dresden, Germany — 3Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany
CoSi is a chiral semimetal hosting an exceptional topology critically depending on the spin-orbit coupling (SOC). Without SOC, the topology features two band-touching nodes with a Chern number of two and nodal planes. With SOC, the two band-touching nodes have a Chern number of four and there is an additional singular Weyl point. To date, the experimental significance of the SOC in CoSi is controversial.
Here, we present our detailed investigation of the bulk band-structure of CoSi with band-structure calculations and angular-dependent de Haas-van Alphen measurements up to 18 T and down to 40 mK. Our results reveal six clearly spin-split bands crossing the Fermi energy, substantiating the significance of the SOC and verifying the topology. Furthermore, we report on three additional quantum-oscillation frequencies which are predicted by calculations but have never been observed before.
Keywords: Quantum oscillations; Fermi surfaces; Band structure; Multifold band-touching nodes; Nodal planes