290S/290K Quantum Materials Seminar: Moritz Hirschmann (RIKEN); Wednesday, February 28 at 2:00 PM Pacific Time in 402 Physics South
Time/Venue: Wednesday, February 28 at 2:00 PM Pacific Time in 402 Physics South and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09
Meeting ID: 995 2349 9113 Passcode: 600704
Host: Ehud Altman / Johannes Mitscherling
Title: Symmetry constraints for topological band crossings
Abstract: Rotational symmetries characterize chiral band crossings on rotation axes, where two or more degenerate bands carry non-zero Chern numbers [1,2]. The topological charge of such band crossings affects the number of surface states and the response functions. We refine the empirical insights into a single expression [3], relating the Chern number with the exchange of rotation eigenvalues. It holds for all (non-)magnetic symmetries for spinless and spinful representations. Equipped with the fundamental laws of chiral band crossings [3], we explain, among others, the chiralities of quadruple Weyl points, identify a band with Chern number 5 in a fourfold point crossing, and classify (representation-)enforced topological nodal planes [3,4,5]. We discuss BaAsPt, MnSi, and NaCu5S3 as possible material realizations.
[1] C. Fang, et al., Phys. Rev. Lett. 108, 266802 (2012)
[2] S. S. Tsirkin, et al., Phys. Rev. B 96, 045102 (2017)
[3] K. Alpin, et al., Phys. Rev. Research 5, 043165 (2023)
[4] M. A. Wilde, et al., Nature 594 (7863), 374-379 (2021)
[5] M. M. Hirschmann, et al., (to be published) (2024)
See the Physics Department calendar for future seminars.