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Flat band carrier confinement in magic-angle twisted bilayer graphene
Nikhil Tilak1, Xinyuan Lai1, Shuang Wu1
1Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
Nature Communications
|July 8, 2021
Summary
Strongly correlated electron physics in magic-angle twisted bilayer graphene is sensitive to doping inhomogeneity. Researchers found that flat bands amplify this inhomogeneity, causing carrier confinement without a magnetic field.
Area of Science:
- Condensed matter physics
- Materials science
Background:
- Magic-angle twisted bilayer graphene offers a unique platform for studying strongly correlated electron physics due to its tunable, flat low-energy bands.
- Sample quality is crucial for isolating correlated phenomena from disorder effects, as these 2D systems are sensitive to doping inhomogeneity.
Purpose of the Study:
- To investigate the impact of doping inhomogeneity on the electronic properties of twisted bilayer graphene.
- To understand how flat bands influence carrier behavior in the presence of potential disorder.
Main Methods:
- Low temperature scanning tunneling spectroscopy
- Planar tunneling junction measurements
Main Results:
- Demonstrated that flat bands in twisted bilayer graphene amplify small doping inhomogeneities.
- Observed unexpected carrier confinement solely due to doping inhomogeneity, mimicking effects previously requiring a strong magnetic field.
Conclusions:
- Doping inhomogeneity significantly impacts the electronic landscape of twisted bilayer graphene.
- The flat bands play a crucial role in amplifying disorder, leading to novel carrier confinement phenomena without external magnetic fields.
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