Anomalies at the Dirac point in graphene

Using polarization dependent ARPES and DFT calculations, we show for the first time that the bands are continuous and linearly dispersive across the Dirac point in graphene on SiC. No energy gap is observed even after boron substitutional doping.

  Pramanik, Thakur et al., Phys. Rev. Lett. 128, 166401 (2022).

We have studied the band structure of epitaxially grown graphene on SiC and its hole-doped compositions by angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT). Linearly s- and p-polarized ARPES reveal the dispersive Dirac bands within the anomalous regime which was hidden due to the finite momentum broadening and the proximity of the bands near the Dirac point. No energy gap is observed at the K point of the Brillouin zone even after boron substitution up to 5% indicating that the gap, if there is any, is below the detection level. The similar scenario near the Dirac point in the doped and undoped cases manifests the robustness of the protection of internal symmetries in the studied doping regime. The band renormalization is found to become more prominent with the increase in hole doping.

These results suggest graphene on SiC as a platform for a new paradigm where properties (mobility, density, etc.) of the Dirac fermions can be tuned significantly to realize exotic science and advanced technology.

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Anomalies at the Dirac point in graphene and its hole-doped compositions
A. Pramanik, S. Thakur, B. Singh, P. Willke, M. Wenderoth, H. Hofsäss, G. Di Santo, L. Petaccia, K. Maiti,
Phys. Rev. Lett. 128, 166401 (2022).
doi: 10.1103/PhysRevLett.128.166401

Last Updated on Wednesday, 20 April 2022 09:10