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Thermally Induced Graphene Rotation on Hexagonal Boron Nitride
Duoming Wang1, Guorui Chen2, Chaokai Li3
1Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Physical Review Letters
|April 9, 2016
Summary
Graphene on hexagonal boron nitride (h-BN) rotates thermally to stable 0° or metastable 30° configurations. This study reveals thermodynamic properties and a method for creating aligned van der Waals heterostructures.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Graphene and hexagonal boron nitride (h-BN) are 2D materials with unique electronic and mechanical properties.
- The interaction between graphene and h-BN can lead to the formation of moiré superlattices, influencing their properties.
- Controlling the relative orientation (twisting angle) between graphene and h-BN is crucial for tailoring heterostructure properties.
Purpose of the Study:
- To investigate the thermally induced rotation of graphene on h-BN.
- To identify the stable and metastable configurations of graphene/h-BN heterostructures.
- To explore methods for achieving aligned van der Waals heterostructures with controlled moiré patterns.
Main Methods:
- Experimental observation of graphene rotation on h-BN using annealing at temperatures above 100°C.
- Theoretical simulations to understand the thermodynamic driving forces for rotation.
- Manipulation of annealing temperature and graphene flake size to control moiré superlattice formation.
Main Results:
- Thermally induced rotation of graphene on h-BN was observed.
- Two stable configurations were identified: a 0° twist angle (most stable) and a 30° twist angle (metastable).
- A critical twist angle of approximately 12±2° was determined, below which rotation favors 0° and above which it favors 30°.
- Moiré superlattices with large spatial periods were successfully fabricated by controlling annealing conditions and flake sizes.
Conclusions:
- The study provides a detailed understanding of the thermodynamic properties governing graphene/h-BN interactions.
- A practical method for obtaining van der Waals heterostructures with aligned lattices has been demonstrated.
- This work offers a pathway for precise control over the structure and properties of 2D material heterostructures.
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