Elemental Topological Dirac Semimetal: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math> -Sn on InSb(111)

Caizhi Xu, Yang‐Hao Chan, Yige Chen, Peng Chen, Xiaoxiong Wang, Catherine Dejoie, Man-Hong Wong, Joseph A. Hlevyack, Hyejin Ryu, Hae‐Young Kee

Abstract

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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• Physical Review Letters - View - PDF
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