Huber Nico, Alpin Kirill, Causer Grace L, Worch Lukas, Bauer Andreas, Benka Georg, Hirschmann Moritz M, Schnyder Andreas P, Pfleiderer Christian, Wilde Marc A
Physik Department, Technische Universität München, D-85748 Garching, Germany.
Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
Phys Rev Lett. 2022 Jul 8;129(2):026401. doi: 10.1103/PhysRevLett.129.026401.
We showcase the importance of global band topology in a study of the Weyl semimetal CoSi as a representative of chiral space group (SG) 198. We identify a network of band crossings comprising topological nodal planes, multifold degeneracies, and Weyl points consistent with the fermion doubling theorem. To confirm these findings, we combined the general analysis of the band topology of SG 198 with Shubnikov-de Haas oscillations and material-specific calculations of the electronic structure and Berry curvature. The observation of two nearly dispersionless Shubnikov-de Haas 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 nodal planes. Hence, irrespective of the spin-orbit coupling strength, SG 198 features always six- and fourfold degenerate crossings at R and Γ that are intimately connected to the topological charges distributed across the network.
我们展示了全局能带拓扑结构在作为手性空间群（SG）198代表的外尔半金属CoSi研究中的重要性。我们确定了一个由拓扑节面、多重简并和外尔点组成的能带交叉网络，这与费米子加倍定理一致。为了证实这些发现，我们将对SG 198能带拓扑结构的一般分析与舒布尼科夫 - 德哈斯振荡以及电子结构和贝里曲率的材料特定计算相结合。观察到两个几乎无色散的舒布尼科夫 - 德哈斯频率分支，为R点处的四个费米面片提供了明确证据，这反映了在与节面相交处底层波函数的对称性强制正交性。因此，无论自旋轨道耦合强度如何，SG 198总是在R和Γ处具有六重和四重简并交叉，它们与分布在网络中的拓扑电荷紧密相连。
