Origin of the Type-II Weyl state in topological antiferromagnetic YbMnBi2

Abstract

Recently, the topological nature of an antiferromagnet YbMnBi2 has been controversial. YbMnBi2 is regarded as a candidate of Type-II Weyl semimetals with magnetic moments of Mn atoms canting about 10° in some studies but as a Dirac semimetal without canting in others. By means of systematical density functional theory calculations, we show the perfect YbMnBi2 bulk has a collinear antiferromagnetic ordering and, naturally, it is a Dirac semimetal. Considering the vital role of magnetic moment canting in generating the Type-II Weyl state, we artificially cant the magnetic moments of Mn atoms and find that YbMnBi2 enters into the Type-II Weyl state from about 2°. Inspired by this and taking into account the possible defects in experiments, we suggest that Bi vacancies in Mn-Bi-Mn bonds, which produce sizable Dzyaloshinskii-Moriya interactions and thereby cant the magnetic moments of Mn atoms, can tune the topological nature of YbMnBi2 from Dirac semimetals to Type-II Weyl semimetals. Our work unveils the possible underlying mechanism for the Type-II Weyl state in YbMnBi2, providing insights into the Weyl state in other magnetic topological materials.

arXiv comment13 pages, 3 figures, 1 table

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Cited by in corpus (3)

• Onsager reciprocal relation between anomalous transverse coefficients of an anisotropic antiferromagnet
• Electrically tunable Gilbert damping in van der Waals heterostructures of two-dimensional ferromagnetic metals and ferroelectrics
• Magnetic excitations in the topological semimetal ${\mathrm{YbMnSb}}_2$