Observation of a Dirac nodal line in AlB2

Daichi Takane, Seigo Souma, Kosuke Nakayama, Takechika Nakamura, Hikaru Oinuma, Kentaro Hori, Kouji Horiba, Hiroshi Kumigashira, Noriaki Kimura, Takashi Takahashi, Takafumi Sato

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20 Citations (Scopus)


We have performed angle-resolved photoemission spectroscopy of AlB2 which is isostructural to high-temperature superconductor MgB2. Using soft-x-ray photons, we accurately determined the three-dimensional bulk band structure and found a highly anisotropic Dirac-cone band at the K point in the bulk hexagonal Brillouin zone. This band disperses downward on approaching the H point while keeping its degeneracy at the Dirac point, producing a characteristic Dirac nodal line along the KH line. We also found that the band structure of AlB2 is regarded as a heavily electron-doped version of MgB2 and is therefore well suited for fully visualizing the predicted Dirac nodal line. The present results suggest that the (Al,Mg)B2 system is a promising platform for studying the interplay among the Dirac nodal line, carrier doping, and possible topological superconducting properties.

Original languageEnglish
Article number041105
JournalPhysical Review B
Issue number4
Publication statusPublished - 2018 Jul 17

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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