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Open Access Publications from the University of California

Elemental Topological Dirac Semimetal: α -Sn on InSb(111)

  • Author(s): Xu, CZ
  • Chan, YH
  • Chen, Y
  • Chen, P
  • Wang, X
  • Dejoie, C
  • Wong, MH
  • Hlevyack, JA
  • Ryu, H
  • Kee, HY
  • Tamura, N
  • Chou, MY
  • Hussain, Z
  • Mo, SK
  • Chiang, TC
  • et al.

© 2017 American Physical Society. Three-dimensional (3D) topological Dirac semimetals (TDSs) are rare but important as a versatile platform for exploring exotic electronic properties and topological phase transitions. A quintessential feature of TDSs is 3D Dirac fermions associated with bulk electronic states near the Fermi level. Using angle-resolved photoemission spectroscopy, we have observed such bulk Dirac cones in epitaxially grown α-Sn films on InSb(111), the first such TDS system realized in an elemental form. First-principles calculations confirm that epitaxial strain is key to the formation of the TDS phase. A phase diagram is established that connects the 3D TDS phase through a singular point of a zero-gap semimetal phase to a topological insulator phase. The nature of the Dirac cone crosses over from 3D to 2D as the film thickness is reduced.

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