INPLANE PARACONDUCTIVITY AND FLUCTUATION-INDUCED MAGNETOCONDUCTIVITY IN BIPERIODIC LAYERED SUPERCONDUCTORS - APPLICATION TO YBA2CU3O7-DELTA

The existing mean-field-like calculations of the different direct and indirect order parameter fluctuation (OFF) contributions to the in-pla ne paraconductivity Delta sigma(ab) and fluctuation-induced magnetocon ductivity Delta(approximate to)sigma(ab) are extended here to layered superconductors with two different interlayer distances and different strengths of the tunneling couplings between adjacent layers (the so-c alled bilayered, or biperiodic layered, superconductors). The calculat ions are performed for magnetic fields H in the weak limit, applied pe rpendicular to the superconducting layers, and at temperatures near bu t above the H=0 mean-field transition temperature, T-c0. We obtain fin al explicit expressions and find that the effects of the layer biperio dicity may be summarized through an effective number N-e of independen t fluctuating superconducting layers per unit cell length, already enc ountered also in our recent calculations of the fluctuation-induced di amagnetism Delta chi(ab) in biperiodic layered superconductors. Our st udy includes some limiting cases of the indirect contributions associa ted with the density of states (DOS) fluctuations, which have been rec ently proposed for Delta sigma(ab) and Delta(approximate to)sigma(ab) for single periodic layered superconductors. As an application, we use then our theoretical results to analyze the paraconductivity and the fluctuation-induced magnetoconductivity recently measured in the a dir ection (nonaffected by the presence of CuO chains) of untwinned YBa2Cu 3O7-delta crystals. This analysis shows that the approaches based on t he conventional Lawrence-Doniach (i.e., single layered) model cannot e xplain simultaneously and quantitatively the intrinsic Delta sigma(a), Delta(approximate to)sigma(a), and Delta chi(ab) in YBa2Cu3O7-delta c rystals, even when the DOS contributions are considered. In contrast, when the double periodicity of this layered superconductor is taken in to account, it is possible to explain consistently and at a quantitati ve level all such experimental data in the reduced temperature region above T-c0 bounded by, approximately, 2x10(-2) and 10(-1), which is ex pected to correspond to the mean-field region without high temperature and nonlocal effects. In the resulting biperiodic scenario, the indir ect(i.e., Maki-Thompson and DOS) contributions to the in-plane Delta s igma(a), and Delta(approximate to)sigma(a) are negligible, confirming our earlier findings which suggested unconventional, pair-breaking, wa ve pairing. Moreover, the direct OFF effects have a dimensionality (tw o-dimensional-three-dimensional) crossover in the mean-field region. O ur results strongly suggest also that to understand at a quantitative level the OFF effects on any in-plane or bulk physical observable in l ayered superconductors with various superconducting layers per unit ce ll length, it is crucial to take into account the influence of such a multiperiodicity.