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arXiv · 1711.11228

Two-Dimensional Dirac Fermions Protected by Space-Time Inversion Symmetry in Black Phosphorus

Jimin Kim·Seung Su Baik·Sung Won Jung·Yeongsup Sohn·Sae Hee Ryu·Hyoung Joon Choi·Bohm-Jung Yang·Keun Su Kim
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Abstract

We report the realization of novel symmetry-protected Dirac fermions in a surface-doped two-dimensional (2D) semiconductor, black phosphorus. The widely tunable band gap of black phosphorus by the surface Stark effect is employed to achieve a surprisingly large band inversion up to ~0.6 eV. High-resolution angle-resolved photoemission spectra directly reveal the pair creation of Dirac points and their moving along the axis of the glide-mirror symmetry. Unlike graphene, the Dirac point of black phosphorus is stable, as protected by spacetime inversion symmetry, even in the presence of spin-orbit coupling. Our results establish black phosphorus in the inverted regime as a simple model system of 2D symmetry-protected (topological) Dirac semimetals, offering an unprecedented opportunity for the discovery of 2D Weyl semimetals.

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Jimin Kim, Seung Su Baik, Sung Won Jung, Yeongsup Sohn, Sae Hee Ryu, Hyoung Joon Choi, Bohm-Jung Yang, Keun Su Kim. 2017-11-30. Two-Dimensional Dirac Fermions Protected by Space-Time Inversion Symmetry in Black Phosphorus. https://doi.org/10.1103/physrevlett.119.226801

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