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Heterostrain and temperature-tuned twist between graphene/h-BN bilayers
1State Key Laboratory of Mechanics and Control of Mechanical Structures, and College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
Scientific Reports
|March 17, 2023
Summary
Heterostrain mechanically controls twist angles in graphene/h-BN bilayers, stabilizing specific angles and enabling band gap modulation. This method offers a new way to design tunable electronic nanodevices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Twistronics leverages atomically stacked 2D materials with small twist angles to tune electronic properties.
- Graphene on hexagonal boron nitride (h-BN) is a model system for exploring twist angle effects.
Purpose of the Study:
- To demonstrate a mechanical strategy for controlling twist angles in graphene/h-BN bilayers.
- To investigate the influence of heterostrain on twist angle stability and band gap modulation.
- To understand the underlying mechanisms of strain-induced twist angle control.
Main Methods:
- Applying controlled heterostrain to graphene flakes on monolayer h-BN.
- Analyzing the resulting twist angle stabilization and Moiré pattern evolution.
- Calculating band gaps of the bilayers under various strain conditions.
- Investigating temperature effects on twist angle stability.
Main Results:
- Heterostrain successfully rotated graphene flakes within ±4° on h-BN.
- Applied constant strains stabilized twist angles at specific values.
- Temperature variations (100–900 K) had negligible effects on twist angles.
- Band gaps were modulated from ~0 to 37 meV with optimized heterostrain and twist angles.
- Heterostrain regulated Moiré pattern evolution, altering the interlayer energy landscape.
Conclusions:
- Heterostrain provides a robust mechanical method to precisely control twist angles in graphene/h-BN bilayers.
- This control enables tunable electronic properties, such as modulated band gaps.
- The findings facilitate the design of novel, rotatable electronic nanodevices based on van der Waals heterostructures.
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