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In this paper, a tunable parallel plate waveguide with a metal plate and a sheet of graphene is presented. The anisotropic conductivity of the graphene sheet submitted to a magnetic field is modeled by a conductivity tensor in which the diagonal and Hall conductivities are derived from the Kubo formula. The Maxwell equations are solved assuming the graphene sheet been biased both with an electric and a magnetic fields. It is shown that in this case a hybrid mode propagates inside the waveguide. The amount of power which propagates in each TE and TM modes can be adjusted by the magnitude of applied fields. Considering the attenuation, the proposed waveguide demonstrate good characteristics in comparison to metal waveguides in the 0.4 to 1 THz frequency band. [ABSTRACT FROM PUBLISHER]

The resistivities of liquid alkaline earth metals are investigated using Ziman formula and the alternative expression based on Kubo formula suggested by Ünal and Alkan [J. Phys. Soc. Jpn. 62 (1993) 2425]. As the input pseudopotential the individual version of the electron-ion potential proposed by Fioalhais and coworkers which was originally developed for solid state is used and static structure factors are derived from the solution of Ornstein-Zernike integral equation with Rogers-Young closure. Good agreement with experiment is found for liquid Mg using both formulas. For Ca, Sr and Ba the agreement between the calculated values using Ziman formula and experimental data is less satisfactory. From present investigations, it is shown that the formula based on Kubo formula suggested by Ünal and Alkan is the better chose for the resistivity calculations of liquid Ca, Sr and Ba metals. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]