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Fabricating van der Waals Heterostructures with Precise Rotational Alignment
Published on: July 5, 2019
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Local atomic stacking and symmetry in twisted graphene trilayers
Isaac M Craig1, Madeline Van Winkle1, Catherine Groschner1
1Department of Chemistry, University of California, Berkeley, CA, USA.
Nature Materials
|January 8, 2024
Summary
Twisted trilayer graphene superlattices exhibit unique correlated electron behaviors and robust superconductivity. Structural relaxation significantly impacts these properties, revealing a novel relaxed structure distinct from prior models.
Area of Science:
- Condensed matter physics
- Materials science
- Nanotechnology
Background:
- Moiré superlattices in twisted trilayer graphene are key models for correlated electron phenomena.
- These systems offer advantages over bilayer analogues, including diverse correlated phases and enhanced superconductivity.
- Spontaneous structural relaxation is hypothesized to influence superconductivity stability in trilayers.
Purpose of the Study:
- To directly investigate the impact of structural relaxation on twisted trilayer graphene.
- To understand how reconstruction modulates local lattice symmetries critical for correlated phases.
- To provide a more accurate structural model for twisted trilayer graphene.
Main Methods:
- Utilized an interferometric four-dimensional scanning transmission electron microscopy (4D-STEM) technique.
- Probed local graphene layer alignment across various trilayer graphene structures.
- Analyzed reconstructed structures to determine lattice symmetries.
Main Results:
- Directly observed and characterized the local layer alignment in twisted trilayer graphene.
- Revealed a significantly relaxed structure that deviates from previous theoretical proposals.
- Demonstrated how reconstruction modulates local lattice symmetries.
Conclusions:
- The study provides direct experimental evidence of structural relaxation in twisted trilayer graphene.
- The findings challenge existing models and offer a new understanding of the relaxed structure.
- This work is crucial for designing and understanding correlated phases and superconductivity in these systems.
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