Specific temperature dependence of pseudogap in YBa2Cu3O7-δ nanolayers

The pseudogap (PG) derived from the analysis of the excess conductivity sigma'(T) in superlattices and double-layer films of YBa2Cu3O7 delta-PrBa2Cu3O7 delta (YBCO-PrBCO), prepared by pulsed laser deposition, is studied for the first time. The sigma'(T) analysis has been performed within the local-pair (LP) model based on the assumption of the paired fermion (LPs) formation in the cuprate high-T-c superconductors (cuprates) below the representative temperature T* >> T-c resulting in the PG opening. Within the model, the temperature dependencies of the PG, Delta*(T), for the samples with different number of the PrBCO layers (N-Pr) were analyzed in the whole temperature range from T* down to T-c. Near T-c, sigma' (T) was found to be perfectly described by the Aslamazov-Larkin (AL) and Hikami-Larkin (HL) [Maki-Thompson (MT) term] fluctuation theories, suggesting the presence of superconducting fluctuations in a relatively large (up to 15 K) temperature range above T-c. All sample parameters were found to change with increase of N-Pr, finally resulting in the appearance of the pronounced maximum of Delta*(T) at high temperatures. The result is most likely due to increasing influence of the intrinsic magnetism of PrBCO (mu(Pr) approximate to 4 mu(B)) and suggests the possibility to search in that way the change of interplay between the superconductivity and magnetism in cuprates.