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Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Imaging universal conductance fluctuations in graphene.
Mario F Borunda1, Jesse Berezovsky, Robert M Westervelt
1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States.
ACS Nano
|April 7, 2011
Summary
Conductance fluctuations (CF) in massless Dirac systems are sensitive to single scatterer motion. CF are suppressed in ballistic systems but approach universal values with stronger disorder, offering insights for graphene devices.
Area of Science:
- Condensed matter physics
- Mesoscopic physics
- Quantum transport
Background:
- Conductance fluctuations (CF) are a key phenomenon in mesoscopic quantum transport.
- Massless Dirac systems, like graphene, exhibit unique electronic properties.
- Understanding scatterer influence is crucial for device applications.
Purpose of the Study:
- Investigate conductance fluctuations (CF) in 2D massless Dirac systems.
- Quantify the sensitivity of conductance to single scatterer motion.
- Determine the limits of universal CF values and their dependence on disorder.
Main Methods:
- Extensive numerical simulations of conductance fluctuations.
- Analysis of systems with varying disorder strength and impurity concentration.
- Theoretical modeling of scatterer-induced conductance changes.
Main Results:
- CF are suppressed in ballistic systems near the Dirac point.
- CF approach universal values at sufficiently strong disorder.
- Single impurity motion comparable to Fermi wavelength causes CF of order e(2)/h.
Conclusions:
- The study reveals limitations to universal CF values in Dirac systems.
- Findings are applicable to graphene with tunable Fermi wavelengths via gate voltages.
- Results provide a basis for testing interference effects in mesoscopic graphene devices.
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