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F. Libisch, S. Rotter, J. Burgdörfer:
"Suppression of size-quantization steps in disordered graphene nanoribbons";
Vortrag: DPG Fruehjahrstagung, 2009, Dresden, Deutschland; 23.03.2009 - 27.03.2009.

We numerically study impurity scattering in graphene nanoribbons as
a function of impurity density and ribbon length. For long ribbons (ribbon length up to 3 micrometers) we observe exponential (Anderson)
localization of the wave function over eight orders of magnitude. To
contrast the role of AB and K-K´ scattering, we compare impurities
that either break or conserve pseudo-spin. By calculating the scattering wave function on the A and B sublattice, we can directly visualize broken pseudo-spin conservation. Using a Fourier transformation allows us to quantitatively assess, for different impurity types, the amount of AB and K-K´ scattering. For perfect ribbons, the conductance features size quantization steps due to the transverse confinement. We find that these steps are strongly suppressed in disordered ribbons for impurities that break the AB-symmetry. In contrast, short-range impurities
that conserve pseudo-spin result in K-K´ scattering and preserve size
quantization steps. Comparison of our results with recent experimental
data suggests that broken AB symmetry plays an important role
in realistic graphene devices.

graphene, quantization, quantum transport