1. Built-in Bernal gap in large-angle-twisted monolayer-bilayer graphene
- Author
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Boschi, Alex, Gebeyehu, Zewdu M., Slizovskiy, Sergey, Mišeikis, Vaidotas, Forti, Stiven, Rossi, Antonio, Watanabe, Kenji, Taniguchi, Takashi, Beltram, Fabio, Fal'ko, Vladimir I., Coletti, Camilla, and Pezzini, Sergio more...
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Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Atomically thin materials offer multiple opportunities for layer-by-layer control of their electronic properties. While monolayer graphene (MLG) is a zero-gap system, Bernal-stacked bilayer graphene (BLG) acquires a finite band gap when the symmetry between the layers' potential energy is broken, usually, via a displacement electric field applied in double-gate devices. Here, we introduce a twistronic stack comprising both MLG and BLG, synthesized via chemical vapor deposition, showing a Bernal gap in the absence of external fields. Although a large ($\sim30^{\circ}$) twist angle decouples the MLG and BLG electronic bands near Fermi level, proximity-induced energy shifts in the outermost layers result in a built-in asymmetry, which requires a displacement field of $0.14$ V/nm to be compensated. The latter corresponds to a $\sim10$ meV intrinsic BLG gap, a value confirmed by our thermal-activation measurements. The present results highlight the role of structural asymmetry and encapsulating environment, expanding the engineering toolbox for monolithically-grown graphene multilayers., Comment: 25 pages, 4 figures and supplementary information more...
- Published
- 2024
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