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Description:

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 large electric field applied in double-gate devices. Here, we introduce an asymmetric twistronic stack comprising both MLG and BLG, synthesized via low-pressure chemical vapor deposition (LP-CVD) on Cu. Although a large (~30°) twist angle decouples the MLG and BLG electronic bands near Fermi level, we find that the layer degeneracy in the BLG subsystem is lifted, producing a gap in the absence of external fields. The built-in interlayer asymmetry originates from proximity-induced energy shifts in the outermost layers and requires a displacement field of 0.14 V/nm to be compensated. The latter corresponds to a ~10 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.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Twistronic stack, Bernal-stacked bilayer graphene, chemical vapor deposition

Date published: 2024-12-01

Publisher: Springer Science and Business Media LLC

Journal:

• Communications Physics (ISSN: 23993650) vol. 7 issue. 1 391

Funding:

• Ministero dell'Istruzione, dell'Università e della Ricerca PE00000023 – NQSTI

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1038/s42005-024-01887-0

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Updated at: 2025-02-07 12:30:26 +0900

Published on MDR: 2025-02-07 12:30:27 +0900