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arXiv · 0711.1005

Universal quantized spin-Hall conductance fluctuation in graphene

Z. H. Qiao·J. Wang·Y. D. Wei·H. Guo
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Abstract

We report a theoretical investigation of quantized spin-Hall conductance fluctuation of graphene devices in the diffusive regime. Two graphene models that exhibit quantized spin-Hall effect (QSHE) are analyzed. Model-I is with unitary symmetry under an external magnetic field $B\ne 0$ but with zero spin-orbit interaction, $t_{SO}=0$. Model-II is with symplectic symmetry where B=0 but $t_{SO} \ne 0$. Extensive numerical calculations indicate that the two models have exactly the same universal QSHE conductance fluctuation value $0.285 e/4π$ regardless of the symmetry. Qualitatively different from the conventional charge and spin universal conductance distributions, in the presence of edge states the spin-Hall conductance shows an one-sided log-normal distribution rather than a Gaussian distribution. Our results strongly suggest that the quantized spin-Hall conductance fluctuation belongs to a new universality class.

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Z. H. Qiao, J. Wang, Y. D. Wei, H. Guo. 2007-11-07. Universal quantized spin-Hall conductance fluctuation in graphene. https://doi.org/10.1103/physrevlett.101.016804

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