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Effect of annealing on a pseudogap state in untwinned YBa(2)Cu(3)O(7−δ) single crystals

The effect of annealing both in the oxygen atmosphere and at room temperatures on physical properties such as the pseudogap (Δ*(T)) and excess conductivity (σ′(T)) of untwined YBa(2)Cu(3)O(7−δ) (YBCO) single crystal with a small deviation from oxygen stoichiometry is studied. It was revealed that as...

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Autores principales: Solovjov, A. L., Petrenko, E. V., Omelchenko, L. V., Vovk, R. V., Goulatis, I. L., Chroneos, A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6592912/
https://www.ncbi.nlm.nih.gov/pubmed/31239510
http://dx.doi.org/10.1038/s41598-019-45286-w
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author Solovjov, A. L.
Petrenko, E. V.
Omelchenko, L. V.
Vovk, R. V.
Goulatis, I. L.
Chroneos, A.
author_facet Solovjov, A. L.
Petrenko, E. V.
Omelchenko, L. V.
Vovk, R. V.
Goulatis, I. L.
Chroneos, A.
author_sort Solovjov, A. L.
collection PubMed
description The effect of annealing both in the oxygen atmosphere and at room temperatures on physical properties such as the pseudogap (Δ*(T)) and excess conductivity (σ′(T)) of untwined YBa(2)Cu(3)O(7−δ) (YBCO) single crystal with a small deviation from oxygen stoichiometry is studied. It was revealed that as the charge carrier density, n(f), increases, Т(с) also slightly increases, whereas the temperature of the pseudogap opening, T*, decreases noticeably, which is consistent with the phase diagram (PD) of cuprates. The excess conductivity in the vicinity of T(c) is represented by the Aslamazov-Larkin and Hikami-Larkin fluctuation theories, illustrating the three-dimensional to two-dimensional (i.e. 3D-2D) crossover with an increase in temperature. The crossover temperature T(0) determines the coherence length along the c axis is ξ(c)(0) = 0.86 Å, that is 2.6 times larger than for optimally doped YBCO single crystals with defects. Taking into account the short coherence length in high-temperature superconductors, in the model of free charge carriers the phase relaxation time of fluctuating Cooper pairs is determined, τ(φ) (100 K) = (4.55 ± 0.4) · 10(−13) s, which is slightly (1.2 times) larger than in well-structured YBCO films, and as in films, does not depend on n(f). It is shown that Δ*(T) at different annealing stages practically does not change its shape. As in the well-structured YBCO films, Δ*(T) demonstrates maximum at T(pair)~124 K which depends weakly on n(f). However, the maximum value of Δ*(T(pair)) increases with increasing n(f), as it follows from the PD of cuprates. Comparing the experimental data with the Peters-Bauer theory we estimated the density of local pairs <n(↑)n(↓)> ≈ 0.3 near T(c) that is a common value for high-temperature superconductors.
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spelling pubmed-65929122019-07-03 Effect of annealing on a pseudogap state in untwinned YBa(2)Cu(3)O(7−δ) single crystals Solovjov, A. L. Petrenko, E. V. Omelchenko, L. V. Vovk, R. V. Goulatis, I. L. Chroneos, A. Sci Rep Article The effect of annealing both in the oxygen atmosphere and at room temperatures on physical properties such as the pseudogap (Δ*(T)) and excess conductivity (σ′(T)) of untwined YBa(2)Cu(3)O(7−δ) (YBCO) single crystal with a small deviation from oxygen stoichiometry is studied. It was revealed that as the charge carrier density, n(f), increases, Т(с) also slightly increases, whereas the temperature of the pseudogap opening, T*, decreases noticeably, which is consistent with the phase diagram (PD) of cuprates. The excess conductivity in the vicinity of T(c) is represented by the Aslamazov-Larkin and Hikami-Larkin fluctuation theories, illustrating the three-dimensional to two-dimensional (i.e. 3D-2D) crossover with an increase in temperature. The crossover temperature T(0) determines the coherence length along the c axis is ξ(c)(0) = 0.86 Å, that is 2.6 times larger than for optimally doped YBCO single crystals with defects. Taking into account the short coherence length in high-temperature superconductors, in the model of free charge carriers the phase relaxation time of fluctuating Cooper pairs is determined, τ(φ) (100 K) = (4.55 ± 0.4) · 10(−13) s, which is slightly (1.2 times) larger than in well-structured YBCO films, and as in films, does not depend on n(f). It is shown that Δ*(T) at different annealing stages practically does not change its shape. As in the well-structured YBCO films, Δ*(T) demonstrates maximum at T(pair)~124 K which depends weakly on n(f). However, the maximum value of Δ*(T(pair)) increases with increasing n(f), as it follows from the PD of cuprates. Comparing the experimental data with the Peters-Bauer theory we estimated the density of local pairs <n(↑)n(↓)> ≈ 0.3 near T(c) that is a common value for high-temperature superconductors. Nature Publishing Group UK 2019-06-25 /pmc/articles/PMC6592912/ /pubmed/31239510 http://dx.doi.org/10.1038/s41598-019-45286-w Text en © The Author(s) 2019 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Solovjov, A. L.
Petrenko, E. V.
Omelchenko, L. V.
Vovk, R. V.
Goulatis, I. L.
Chroneos, A.
Effect of annealing on a pseudogap state in untwinned YBa(2)Cu(3)O(7−δ) single crystals
title Effect of annealing on a pseudogap state in untwinned YBa(2)Cu(3)O(7−δ) single crystals
title_full Effect of annealing on a pseudogap state in untwinned YBa(2)Cu(3)O(7−δ) single crystals
title_fullStr Effect of annealing on a pseudogap state in untwinned YBa(2)Cu(3)O(7−δ) single crystals
title_full_unstemmed Effect of annealing on a pseudogap state in untwinned YBa(2)Cu(3)O(7−δ) single crystals
title_short Effect of annealing on a pseudogap state in untwinned YBa(2)Cu(3)O(7−δ) single crystals
title_sort effect of annealing on a pseudogap state in untwinned yba(2)cu(3)o(7−δ) single crystals
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6592912/
https://www.ncbi.nlm.nih.gov/pubmed/31239510
http://dx.doi.org/10.1038/s41598-019-45286-w
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