Single-Layer Behavior and Its Breakdown in Twisted Graphene Layers
Author(s)
Luican, A.; Li, Guohong; Reina, Alfonso; Kong, Jing; Nair, R. R.; Novoselov, Kostya S.; Geim, A. K.; Andrei, E. Y.; ... Show more Show less
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We report high magnetic field scanning tunneling microscopy and Landau level spectroscopy of twisted graphene layers grown by chemical vapor deposition. For twist angles exceeding ∼3° the low energy carriers exhibit Landau level spectra characteristic of massless Dirac fermions. Above 20° the layers effectively decouple and the electronic properties are indistinguishable from those in single-layer graphene, while for smaller angles we observe a slowdown of the carrier velocity which is strongly angle dependent. At the smallest angles the spectra are dominated by twist-induced van Hove singularities and the Dirac fermions eventually become localized. An unexpected electron-hole asymmetry is observed which is substantially larger than the asymmetry in either single or untwisted bilayer graphene.
Date issued
2011-03Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science; Massachusetts Institute of Technology. Department of Materials Science and EngineeringJournal
Physical Review Letters
Publisher
American Physical Society
Citation
Luican, A. et al. “Single-Layer Behavior and Its Breakdown in Twisted Graphene Layers.” Physical Review Letters 106.12 (2011) © 2011 American Physical Society
Version: Final published version
ISSN
0031-9007