Moiré Superlattice Effects and Band Structure Evolution in Near-30-Degree Twisted Bilayer Graphene
| Autor: | Matthew J. Hamer, Alessio Giampietri, Viktor Kandyba, Francesca Genuzio, Tevfik O. Menteş, Andrea Locatelli, Roman V. Gorbachev, Alexei Barinov, Marcin Mucha-Kruczyński |
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| Rok vydání: | 2022 |
| Předmět: |
Condensed Matter - Mesoscale and Nanoscale Physics
moiré superlattices General Engineering General Physics and Astronomy stacking-dependent electronic properties Physics and Astronomy(all) minigaps Materials Science(all) General Materials Science twisted bilayer graphene van Hove singularities photoemission Engineering(all) |
| Zdroj: | Hamer, M J, Giampietri, A, Kandyba, V, Genuzio, F, Menteş, T O, Locatelli, A, Gorbachev, R V, Barinov, A & Mucha-Kruczynski, M 2022, ' Moiré Superlattice Effects and Band Structure Evolution in Near-30-Degree Twisted Bilayer Graphene ', ACS Nano, vol. 16, no. 2, pp. 1954-1962 . https://doi.org/10.1021/acsnano.1c06439 Hamer, M J, Giampietri, A, Kandyba, V, Genuzio, F, Menteş, T O, Locatelli, A, Gorbachev, R V, Barinov, A & Mucha-kruczyński, M 2022, ' Moiré Superlattice Effects and Band Structure Evolution in Near-30-Degree Twisted Bilayer Graphene ', ACS Nano . https://doi.org/10.1021/acsnano.1c06439 |
| ISSN: | 1936-086X |
| Popis: | In stacks of two-dimensional crystals, mismatch of their lattice constants and misalignment of crystallographic axes lead to formation of moir\'{e} patterns. We show that moir\'{e} superlattice effects persist in twisted bilayer graphene (tBLG) with large twists and short moir\'{e} periods. Using angle-resolved photoemission, we observe dramatic changes in valence band topology across large regions of the Brillouin zone, including the vicinity of the saddle point at $M$ and across 3 eV from the Dirac points. In this energy range, we resolve several moir\'{e} minibands and detect signatures of secondary Dirac points in the reconstructed dispersions. For twists $\theta>21.8^{\circ}$, the low-energy minigaps are not due to cone anti-crossing as is the case at smaller twist angles but rather due to moir\'{e} scattering of electrons in one graphene layer on the potential of the other which generates intervalley coupling. Our work demonstrates robustness of mechanisms which enable engineering of electronic dispersions of stacks of two-dimensional crystals by tuning the interface twist angles. It also shows that large-angle tBLG hosts electronic minigaps and van Hove singularities of different origin which, given recent progress in extreme doping of graphene, could be explored experimentally. Comment: main text: 25 pages, 5 figures; supplement: 22 pages, 7 figures |
| Databáze: | OpenAIRE |
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