14,412 research outputs found

    Transition behavior of k-surface from hyperbola to ellipse

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    The transition behavior of the k-surface of a lossy anisotropic indefinite slab is investigated. It is found that, if the material loss is taken into account, the k-surface does not show a sudden change from hyperbola to the ellipse when one principle element of the permittivity tensor changes from negative to positive. In fact, after introducing a small material loss, the shape of the k-surface can be a combination of a hyperbola and an ellipse, and a selective high directional transmission can be obtained in such a slab

    Head related transfer function experiment and modeling

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    Universal quantized spin-Hall conductance fluctuation in graphene

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    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 B0B\ne 0 but with zero spin-orbit interaction, tSO=0t_{SO}=0. Model-II is with symplectic symmetry where B=0 but tSO0t_{SO} \ne 0. Extensive numerical calculations indicate that the two models have exactly the same universal QSHE conductance fluctuation value 0.285e/4π0.285 e/4\pi 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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