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Published on: July 24, 2015
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Critical level statistics for weakly disordered graphene
E Amanatidis1, I Kleftogiannis, D E Katsanos
1Department of Physics, University of Ioannina, Ioannina 45110, Greece.
Summary
Weakly disordered graphene with zigzag edges exhibits intermediate level statistics, not chaotic or localized. This suggests critical quantum transport via edge states in topological insulators, unlike ordinary Anderson insulators.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Mechanics
Background:
- In two dimensions, chaotic level statistics with Wigner spacing distribution are theoretically expected for massless fermions in the Dirac region.
- Graphene, a 2D material, exhibits unique electronic properties due to its massless Dirac fermions.
Purpose of the Study:
- To investigate the level statistics of weakly disordered finite graphene samples with zigzag edges.
- To understand the nature of quantum transport in graphene under varying disorder strengths.
Main Methods:
- Analysis of level spacing distribution P(S) for finite graphene samples with zigzag edges.
- Comparison of obtained statistics with theoretical predictions for chaotic (Wigner) and localized (Poisson) systems.
Main Results:
- The level statistics for weakly disordered graphene with zigzag edges were neither chaotic (Wigner) nor localized (Poisson).
- The observed statistics resemble those at the critical point of the Anderson metal-insulator transition.
- For strong disorder, graphene behaves as an ordinary Anderson insulator with Poisson statistics.
Conclusions:
- Weakly disordered graphene with critical level statistics exhibits quantum transport via edge states, similar to topological insulators.
- The findings bridge the understanding between chaotic, localized, and critical phenomena in disordered 2D electron systems.
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