Unconventional Sequence of Fractional Quantum Hall States in Suspended Graphene

Graphene provides a rich platform to study many-body effects, owing to its massless chiral charge carriers and the fourfold degeneracy arising from their spin and valley degrees of freedom. We use a scanning single-electron transistor to measure the local electronic compressibility of suspended grap...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2012-09, Vol.337 (6099), p.1196-1199
Main Authors: Feldman, Benjamin E., Krauss, Benjamin, Smet, Jurgen H., Yacoby, Amir
Format: Article
Language:English
Subjects:
Charge carriers
Compressibility
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Correlations
Electric potential
Electron density
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Electronic transport in interface structures
Electrons
Energy gaps
Exact sciences and technology
Fermions
Fractions
Graphene
Integers
Magnetic fields
Materials science
Monitoring
Physics
Quantum Hall effect
Quantum hall effect (including fractional)
Quantum physics
Semiconductors
Voltage
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Summary:Graphene provides a rich platform to study many-body effects, owing to its massless chiral charge carriers and the fourfold degeneracy arising from their spin and valley degrees of freedom. We use a scanning single-electron transistor to measure the local electronic compressibility of suspended graphene, and we observed an unusual pattern of incompressible fractional quantum Hall states that follows the standard composite fermion sequence between filling factors ν = 0 and 1 but involves only even-numerator fractions between ν = 1 and 2. We further investigated this surprising hierarchy by extracting the corresponding energy gaps as a function of the magnetic field. The sequence and relative strengths of the fractional quantum Hall states provide insight into the interplay between electronic correlations and the inherent symmetries of graphene.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1224784