Unquantized anomalies in topological semimetals

dc.contributor.author Gioia, L.
dc.contributor.author Wang, Chong
dc.contributor.author Burkov, A. A.
dc.date.accessioned 2023-05-16T14:59:08Z
dc.date.available 2023-05-16T14:59:08Z
dc.date.issued 2021-10-22
dc.description.abstract Topological semimetals are a new class of metallic materials, which exist at band fillings that ordinarily correspond to insulators or compensated accidental semimetals with zero Luttinger volume. Their metallicity is a result of nontrivial topology in momentum space and crystal symmetry, wherein topological charges may be assigned to point band-touching nodes, preventing gap opening, unless protecting crystal symmetries are violated. These topological charges, however, are defined from noninteracting band eigenstates, which raises the possibility that the physics of topological semimetals may be modified qualitatively by electron-electron interactions. Here we ask the following question: what makes the topological semimetals nontrivial beyond band theory? Alternatively, can strong electron-electron interactions open a gap in topological semimetals without breaking the protecting symmetries or introducing topological order? We demonstrate that the answer is generally no, and what prevents it is their topological response or quantum anomalies. While this is familiar in the case of magnetic Weyl semimetals, where the topological response takes the form of an anomalous Hall effect, analogous responses in other types of topological semimetals are more subtle and involve crystal symmetry as well as electromagnetic gauge fields. Physically these responses are detectable as fractional symmetry charges induced on certain gauge defects. We discuss the cases of type-I Dirac semimetals and time-reversal invariant Weyl semimetals in detail. For type-I Dirac semimetals, we also show that the anomaly vanishes, in a nontrivial manner, if the momenta of the Dirac nodes satisfy certain exceptional conditions.
dc.description.comments This article is published as Gioia, Lei, Chong Wang, and A. A. Burkov. "Unquantized anomalies in topological semimetals." Physical Review Research 3, no. 4 (2021): 043067. DOI: 10.1103/PhysRevResearch.3.043067. Copyright 2021 The Authors. Attribution 4.0 International (CC BY 4.0). DOE Contract Number(s): AC02-07CH11358. Posted with permission.
dc.identifier.other 1833023
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/Nr1VNKnz
dc.language.iso en
dc.publisher Iowa State University Digital Repository, Ames IA (United States)
dc.relation.ispartofseries IS-J 10639
dc.source.uri https://doi.org/10.1103/PhysRevResearch.3.043067 *
dc.subject.disciplines DegreeDisciplines::Physical Sciences and Mathematics::Physics
dc.title Unquantized anomalies in topological semimetals
dc.type Article
dspace.entity.type Publication
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