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Insulating behavior at the neutrality point in single-layer graphene.
F Amet1, J R Williams, K Watanabe
1Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
Physical Review Letters
|June 11, 2013
Summary
At very low temperatures, graphene
Area of Science:
- Condensed matter physics
- Materials science
Background:
- Graphene's electronic properties at low temperatures are crucial for understanding quantum phenomena.
- Boron nitride is a key substrate for high-quality graphene devices.
Purpose of the Study:
- Investigate low-temperature conductance in graphene on boron nitride.
- Characterize the insulating behavior at the Dirac point.
Main Methods:
- Measurements of electrical conductance in graphene on boron nitride.
- Temperature variation down to 20 mK.
- Application of perpendicular magnetic fields.
Main Results:
- Observed diverging resistivity with power-law behavior at low temperatures.
- Reached several megohms per square resistivity at 20 mK.
- Transitioned to a broken-valley-symmetry, ν=0 quantum Hall state under magnetic field.
Conclusions:
- The insulating behavior at zero magnetic field is attributed to broken valley symmetry.
- This contrasts with typical conductivity saturation observed in other systems.
- Suggests novel electronic states in graphene/boron nitride heterostructures.
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