FLUCTUATION-INDUCED DIAMAGNETISM VERSUS PARACONDUCTIVITY IN Y1BA2CU3O7-DELTA SINGLE-CRYSTALS

The rounding effects above the superconducting transition of the elect rical resistivity and of the magnetic susceptibility in low magnetics fields have been measured in the same YBa2Cu3O7-delta (YBCO) single cr ystals. When analyzed in terms of independent gaussian fluctuations of the superconducting order parameter in layered materials, an scenario compatible with these experimental results is: Absence of appreciable Maki-Thompson contribution to the paraconductivity, xi(ab)(0) = (10 /- 2) angstrom, xi(C)(0) = (1.2 +/- 0.3) angstrom, d(e) = s = 11.7 ang strom, and conventional 1s0 wave pairing or one complex component unco nventional pairing.