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Universal spin-Hall conductance fluctuations in two dimensions
We report a theoretical investigation on spin-Hall conductance fluctuation of
disordered four terminal devices in the presence of Rashba or/and Dresselhaus
spin-orbital interactions in two dimensions. As a function of disorder, the
spin-Hall conductance shows ballistic, diffusive and insulating
transport regimes. For given spin-orbit interactions, a universal spin-Hall
conductance fluctuation (USCF) is found in the diffusive regime. The value of
the USCF depends on the spin-orbit coupling , but is independent of
other system parameters. It is also independent of whether Rashba or
Dresselhaus or both spin-orbital interactions are present. When is
comparable to the hopping energy , the USCF is a universal number . The distribution of crosses over from a Gaussian distribution
in the metallic regime to a non-Gaussian distribution in the insulating regime
as the disorder strength is increased.Comment: to be published in Phys. Rev. Lett., 4 figure
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