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Rotational disorder in twisted bilayer graphene.
Thomas E Beechem1, Taisuke Ohta, Bogdan Diaconescu
1Sandia National Laboratories , Albuquerque, New Mexico, United States.
ACS Nano
|January 28, 2014
Summary
Rotational disorder and strain in twisted bilayer graphene (TBG) were quantified. Interlayer interactions remain resilient despite these imperfections, paving the way for designer 2D heterostructures.
Area of Science:
- Materials Science
- Condensed Matter Physics
Background:
- Stacking two-dimensional (2D) crystals often introduces imperfections.
- Understanding these imperfections is crucial for controlling material properties.
Purpose of the Study:
- To quantify rotational disorder and strain in twisted bilayer graphene (TBG).
- To investigate the impact of these imperfections on emergent Raman response.
- To assess the resilience of interlayer interactions in TBG.
Main Methods:
- Combined Raman spectroscopy and low-energy electron diffraction (LEED) imaging.
- Analysis of large single-crystalline grains (50-100 μm) with varying twist angles.
- Characterization of subgrain structures (∼1 μm) and associated strain variations.
Main Results:
- Twist angle variations (∼2°) across grains led to significant changes in Raman response.
- Rotational disorder arose from variations in local twist angles between subgrains.
- Subgrains exhibited minimal twist angle variation (ΔΘ ∼ 0.1°) and coupled with 0.3% strain.
- Emergent Raman response was altered but not eliminated by disorder and strain.
Conclusions:
- Interlayer interactions in TBG are robust against strain and rotational disorder.
- This resilience supports the development of designer 2D solid heterostructures.
- Transfer processes can be utilized to create tailored 2D materials.
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