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Valley Hall effect is observed in asymmetric single-layer and bilayer graphene systems. In single-layer graphene systems, asymmetry is introduced by aligning graphene with hexagonal boron nitride (hBN) with a near-zero twist angle, breaking the sub-lattice symmetry. Although a similar approach is used in bilayer graphene to break the layer symmetry and thereby observe the valley Hall effect, the bilayer graphene is sandwiched with hBN on both sides in those studies. This study looks at a much simpler, non-encapsulated structure where hBN is present only at the top of graphene. The crystallographic axes of both hBN and bilayer graphene are aligned. A clear signature of the valley Hall effect through non-local resistance measurement (RNL) is observed. The observed non-local resistance can be manipulated by applying a displacement field across the heterostructure. Furthermore, the electronic band structure and Berry curvature calculations validate the experimental observations.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Valley Hall effect, Bilayer graphene, Non-local resistance (RNL)

Date published: 2023-08-31

Publisher: Wiley

Journal:

• Advanced Physics Research (ISSN: 27511200) vol. 3 issue. 1 2300064

Funding:

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

MDR DOI:

First published URL: https://doi.org/10.1002/apxr.202300064

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Updated at: 2025-08-01 16:30:22 +0900

Published on MDR: 2025-08-01 16:18:21 +0900