Unraveling Quantum Hall Breakdown in Bilayer Graphene with Scanning Gate Microscopy

Investigating the structure of quantized plateaus in the Hall conductance of graphene is a powerful way of probing its crystalline and electronic structure and will also help to establish whether graphene can be used as a robust standard of resistance for quantum metrology. We use low-temperature sc...

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Bibliographic Details
Published in:Nano letters 2012-11, Vol.12 (11), p.5448-5454
Main Authors: Connolly, M. R, Puddy, R. K, Logoteta, D, Marconcini, P, Roy, M, Griffiths, J. P, Jones, G. A. C, Maksym, P. A, Macucci, M, Smith, C. G
Format: Article
Language:English
Subjects:
Breakdown
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Conductance
Cross-disciplinary physics: materials science
rheology
Density
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals
Exact sciences and technology
Fullerenes and related materials
diamonds, graphite
Gates
Graphene
Materials science
Microscopy
Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals
Nanostructure
Physics
Scanning
Specific materials
Structure of solids and liquids
crystallography
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Summary:Investigating the structure of quantized plateaus in the Hall conductance of graphene is a powerful way of probing its crystalline and electronic structure and will also help to establish whether graphene can be used as a robust standard of resistance for quantum metrology. We use low-temperature scanning gate microscopy to image the interplateau breakdown of the quantum Hall effect in an exfoliated bilayer graphene flake. Scanning gate images captured during breakdown exhibit intricate patterns where the conductance is strongly affected by the presence of the scanning probe tip. The maximum density and intensity of the tip-induced conductance perturbations occur at half-integer filling factors, midway between consecutive quantum Hall plateau, while the intensity of individual sites shows a strong dependence on tip-voltage. Our results are well-described by a model based on quantum percolation which relates the points of high responsivity to tip-induced scattering in a network of saddle points separating localized states.
ISSN:1530-6984
1530-6992
DOI:10.1021/nl3015395