Abstract
By using two randomly oriented polycrystalline YBa2Cu3O7 − δ samples
with masses as big as 0.63 g and 0.90 g, but almost optimally doped
(Tc0 ≃ 90.8 K and 92.0 K) and with excellent
stoichiometric homogeneity, the in-plane fluctuation-induced diamagnetism was determined,
for the first time in any superconductor, well inside the so-called short wavelength regime
in the zero-magnetic-field limit, which corresponds to reduced temperatures,
≡ ln (T/Tc0), above typically = 0.1. It is then shown
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.