Emergence of superlattice Dirac points in graphene on hexagonal boron nitride

Matthew Yankowitz, Jiamin Xue, Daniel Cormode, Javier D. Sanchez-Yamagishi, K. Watanabe, T. Taniguchi, Pablo Jarillo-Herrero, Philippe Jacquod, Brian J Leroy

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Abstract

The Schrödinger equation dictates that the propagation of nearly free electrons through a weak periodic potential results in the opening of bandgaps near points of the reciprocal lattice known as Brillouin zone boundaries 1. However, in the case of massless Dirac fermions, it has been predicted that the chirality of the charge carriers prevents the opening of a bandgap and instead new Dirac points appear in the electronic structure of the material 2,3. Graphene on hexagonal boron nitride exhibits a rotation-dependent moiré pattern 4,5. Here, we show experimentally and theoretically that this moiré pattern acts as a weak periodic potential and thereby leads to the emergence of a new set of Dirac points at an energy determined by its wavelength. The new massless Dirac fermions generated at these superlattice Dirac points are characterized by a significantly reduced Fermi velocity. Furthermore, the local density of states near these Dirac cones exhibits hexagonal modulation due to the influence of the periodic potential.

Original languageEnglish (US)
Pages (from-to)382-386
Number of pages5
JournalNature Physics
Volume8
Issue number5
DOIs
Publication statusPublished - May 2012

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Yankowitz, M., Xue, J., Cormode, D., Sanchez-Yamagishi, J. D., Watanabe, K., Taniguchi, T., ... Leroy, B. J. (2012). Emergence of superlattice Dirac points in graphene on hexagonal boron nitride. Nature Physics, 8(5), 382-386. https://doi.org/10.1038/nphys2272