Filters

2003 - 20062

More filters

20192
Reset filters

Settings

End date: 2009 × Start date: 2000 × Publisher: São Carlos : Universidade Federal de São Carlos × WGL Institute: IFWD ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Electronic structure and aspects of unconventional superconductivity in NaxCoO2.yH2O
    (São Carlos : Universidade Federal de São Carlos, 2003) Rosner, H.; Drechsler, S.-L.; Fuchs, G.; Handstein, A.; Wälte, A.; Müller, K.-H.
    We examine the electronic structure of NaxCoO2.yH2O within the local density approximation. The parametrization of the band which forms the largest hole-Fermi surface centered at G shows significant deviations from what is frequently assumed in recent sophisticated theoretical studies. In particular, the commonly used nearest neighbor approaches in the framework of single band pictures are found to be unrealistic. The special role of H2O in screening the disorder in the charge reservoir is briefly discussed and compared with the case of Y1–xCaxCu3O6+d.
  • Thumbnail Image
    Item
    Magnetic field effects of double-walled carbon nanotubes
    (São Carlos : Universidade Federal de São Carlos, 2006) Latgé, A.; Grimm, D.; Ferreira, M.S.
    A theoretical discussion of electronic and transport properties of a particular family of double-wall carbon nanotubes, named commensurate structures of the armchair type (n,n)@(2n,2n) is addressed. A single p-band tight binding hamiltonian is considered and the magnetic field is theoretically described by following the Peierls approximation into the hopping energies. Our emphasis is put on investigating the main effects of the geometrical aspects and relative positions of the tubes on the local density of states and on the conductance of the system. By considering intershell interactions between a set of neighboring atoms on the walls of the inner and outer tubes, we study the possibility of founding Aharonov-Bohm effects in the DWCNs when a magnetic field is applied along the axial direction.