PS04 Berry's phase in the multimode Peierls states(Topological Aspects of Solid State Physics)

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Dephasing by time-dependent random potentials

Diffusion of electrons in a two-dimensional system with time-dependent random potentials is investigated numerically. The correction to the conductivity due to inelastic scatterings by oscillating potentials is shown to be a universal function of the frequency $\omega$, which is consistent with the weak localization prediction $(e^2)/(3\pi^2 \hbar) log \omega$.Comment: 4 pages, RevTeX, 3 postscript figures, accepted in J. Phys. Soc. Jpn.(1997)Ap

Quantum Hall plateau transition in graphene with spatially correlated random hopping

We investigate how the criticality of the quantum Hall plateau transition in disordered graphene differs from those in the ordinary quantum Hall systems, based on the honeycomb lattice with ripples modeled as random hoppings. The criticality of the graphene-specific n=0 Landau level is found to change dramatically to an anomalous, almost exact fixed point as soon as we make the random hopping spatially correlated over a few bond lengths. We attribute this to the preserved chiral symmetry and suppressed scattering between K and K' points in the Brillouin zone. The results suggest that a fixed point for random Dirac fermions with chiral symmetry can be realized in free-standing, clean graphene with ripples.Comment: 5 pages, 4 figures, changes in figure