Realization of a Type-II Nodal-Line Semimetal in Mg 3 Bi 2

Tay Rong Chang, Ivo Pletikosic, Tai Kong, Guang Bian, Angus Huang, Jonathan Denlinger, Satya K. Kushwaha, Boris Sinkovic, Horny Tay Jeng, Tonica Valla, Weiwei Xie, Robert J. Cava

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14 Scopus citations

Abstract

Nodal-line semimetals (NLSs) represent a new type of topological semimetallic phase beyond Weyl and Dirac semimetals in the sense that they host closed loops or open curves of band degeneracies in the Brillouin zone. Parallel to the classification of type-I and type-II Weyl semimetals, there are two types of NLSs. The type-I NLS phase has been proposed and realized in many compounds, whereas the exotic type-II NLS phase that strongly violates Lorentz symmetry has remained elusive. First-principles calculations show that Mg 3 Bi 2 is a material candidate for the type-II NLS. The band crossing is close to the Fermi level and exhibits the type-II nature of the nodal line in this material. Spin–orbit coupling generates only a small energy gap (≈35 meV) at the nodal points and does not negate the band dispersion of Mg 3 Bi 2 that yields the type-II nodal line. Based on this prediction, Mg 3 Bi 2 single crystals are synthesized and the presence of the type-II nodal lines in the material is confirmed. The angle-resolved photoemission spectroscopy measurements agree well with the first-principles results below the Fermi level and thus strongly suggest Mg 3 Bi 2 as an ideal material platform for studying the as-yet unstudied properties of type-II nodal-line semimetals.

Original languageEnglish (US)
Article number1800897
JournalAdvanced Science
Volume6
Issue number4
DOIs
StatePublished - Feb 20 2019

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Chemical Engineering(all)
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Keywords

  • Mg Bi
  • angle-resolved photoemission spectroscopy
  • density functional theory calculations
  • topological materials
  • topological semimetals

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    Chang, T. R., Pletikosic, I., Kong, T., Bian, G., Huang, A., Denlinger, J., Kushwaha, S. K., Sinkovic, B., Jeng, H. T., Valla, T., Xie, W., & Cava, R. J. (2019). Realization of a Type-II Nodal-Line Semimetal in Mg 3 Bi 2 Advanced Science, 6(4), [1800897]. https://doi.org/10.1002/advs.201800897