Fluctuation-induced diamagnetism at high reduced temperatures in YBa2Cu3O7-delta superconductors

By using two randomly oriented polycrystalline YBa2Cu3O7-delta samples with masses as big as 0.63 g and 0.90 g, but almost optimally doped (T-c0 simil ar or equal to 90.8 K and 92.0 K) and with excellent stoichiometric homogen eity, the in-plane fluctuation-induced diamagnetism was determined, for the rst time in any superconductor, well inside the so-called short wavelength regime in the zero-magnetic-field limit, which corresponds to reduced temp eratures, epsilon = ln(T/T-c0), above typically epsilon = 0.1. It is then s hown that these measurements may be explained in terms of the Schmidt limit of the Gaussian-Ginzburg-Landau approach for bilayered superconductors by introducing a total-energy cut-off in the fluctuation spectrum.