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arXiv · 1804.06119

Specific temperature dependence of pseudogap in YBa$_2$Cu$_3$O$_{7-δ}$ nanolayers

A. L. Solovjov·L. V. Omelchenko·V. B. Stepanov·R. V. Vovk·H. -U. Habermeier·H. Lochmajer·P. Przysłupski·K. Rogacki
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Abstract

The pseudogap (PG) derived from the analysis of the excess conductivity $σ'(T)$ in superlattices and double-layer films of $YBa_2Cu_3O_{7-δ}$-$PrBa_2Cu_3O_{7-δ}$(YBCO-PrBCO), prepared by pulsed laser deposition, is studied for the first time. The $σ'(T)$ 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 $T^*\gg T_c$ resulting in the PG opening. Within the model, the temperature dependencies of the PG, $Δ^*(T)$, 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 $T_c$, excess conductivity was found to be perfectly described by the Aslamasov-Larkin and Hikami-Larkin (Maki-Thompson 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 $Δ^*(T)$ at high temperatures. The result is most likely due to increasing influence of the intrinsic magnetism of PrBCO ($μ_{Pr}\approx 4\,μ_B$) and suggests the possibility to search in that way the change of interplay between the superconductivity and magnetism in cuprates.

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A. L. Solovjov, L. V. Omelchenko, V. B. Stepanov, R. V. Vovk, H. -U. Habermeier, H. Lochmajer, P. Przysłupski, K. Rogacki. 2018-04-17. Specific temperature dependence of pseudogap in YBa$_2$Cu$_3$O$_{7-δ}$ nanolayers. https://doi.org/10.1103/physrevb.94.224505

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