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Description:

In twisted layered materials (t-LMs), an inter-layer rotation can break inversion symmetry and create an interfacial array of staggered out-of-plane polarization due to AB/BA stacking registries. This symmetry breaking can also trigger the formation of edge in-plane polarizations localized along the perimeter of AB/BA regions (i.e., saddle point domains). However, a comprehensive experimental investigation of these features is still lacking. Here, we use piezo force microscopy to probe the electromechanical behavior of twisted hexagonal boron nitride (t-hBN). For parallel stacking alignment of t-hBN, we reveal very narrow (width ~ 10 nm) saddle point in-plane polarizations, which we also measure in the anti-parallel configuration. These localized polarizations can still be found on a multiply stacked t-hBN structure, determining the formation of a double moiré. Our findings imply that polarizations in t-hBN do not only point in the out-of-plane direction but also show an in-plane component, giving rise to a much more complex 3D polarization field.

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• Creative Commons BY Attribution 4.0 International
  

Keyword: twisted hBN
, moiré superlattices, piezo force microscopy


Date published: 2025-05-06

Publisher: American Chemical Society (ACS)

Journal:

• ACS Nano (ISSN: 19360851) vol. 19 issue. 17 p. 16297-16306

Funding:

• Engineering and Physical Sciences Research Council EP/K01711X/1
• Engineering and Physical Sciences Research Council EP/K017144/1
• Engineering and Physical Sciences Research Council EP/L016087/1
• Engineering and Physical Sciences Research Council EP/N010345/1
• Engineering and Physical Sciences Research Council EP/V000055/1
• Engineering and Physical Sciences Research Council EP/X015742/1
• European Research Council 817794
• Fondazione Cariplo 2019-3923
• Graphene Flagship

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

MDR DOI:

First published URL: https://doi.org/10.1021/acsnano.4c12315

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Updated at: 2026-02-17 12:30:06 +0900

Published on MDR: 2026-02-17 09:10:58 +0900