Universal Landauer conductance in chiral symmetric 2d systems

We study transport properties of an arbitrarily shaped ultraclean graphene sheet, adiabatically connected to leads,composed by the same material. If the localized interactions do not destroy chiral symmetry, we show that the conductance is quantized, since it is dominated by the quasi one-dimensional leads. As an example, we show that smooth structural deformations of the graphene plane do not modify the conductance quantization.Comment: 6 pages, no figure

The nematic phase in stripe forming systems within the self consistent screening approximation

We show that in order to describe the isotropic-nematic transition in stripe forming systems with isotropic competing interactions of the Brazovskii class it is necessary to consider the next to leading order in a 1/N approximation for the effective Hamiltonian. This can be conveniently accomplished within the self-consistent screening approximation. We solve the relevant equations and show that the self-energy in this approximation is able to generate the essential wave vector dependence to account for the anisotropic character of two-point correlation function characteristic of a nematic phase.Comment: 8 pages, 4 figure