FLUCTUATION CONDUCTIVITY OF LAYERED SUPERCONDUCTORS IN A PERPENDICULAR MAGNETIC-FIELD

The leading contributions to the c-axis conductivity of layered superc onductors arising from superconducting fluctuations of the order param eter are discussed for arbitrary intralayer scattering. The contributi ons from fluctuations of the normal quasiparticle density of states ar e shown to be opposite in sign to the Aslamazov-Larkin and Maki-Thomps on contributions, leading to a peak in the overall c-axis resistivity rho(c)(T) above T(c). This peak is enhanced by a magnetic field H\\-c. With increasing H, the relative peak maximum in rho(c)(TH) increases in magnitude and is shifted to lower temperatures by an amount proport ional to H-2 for weak fields and to H for strong fields. For compariso n, the fluctuation conductivity parallel to the layers has been calcul ated including the fluctuations of the normal density of states. Our r esults are discussed in regard to recent experiments with YBa2Cu3O7-de lta and Bi2Sr2CaCu2O8+delta.