Evolution of the pseudogap temperature dependence in YBa2Cu3O7-δ films under the influence of a magnetic field
Petrenko E.V. Rogacki K. Terekhov A.V. Bludova L.V. Kolesnichenko Y.A. Shytov N.V. Sergeyev D.M. Lähderanta E. Solovjov A.L.
1 April 2024American Institute of Physics
Low Temperature Physics
2024#50Issue 4299 - 307 pp.
The evolution of the temperature dependence of the pseudogap Δ*(T) in optimally doped (OD) YBa2Cu3O7-δ (YBCO) films with the superconducting critical temperature Tc = 88.7 K under the influence of a magnetic field B has been studied in detail. It has been established that the shape of Δ*(T) for various B over the entire range from the pseudogap opening temperature T* to T01, below which superconducting fluctuations occur, has a wide maximum at the BEC-BCS crossover temperature Tpair, which is typical for OD films and untwinned YBCO single crystals. T* was shown to be independent on B, whereas Tpair shifts to the low-temperature region along with the increase in B, while the maximum value of Δ*(Tpair) remains practically constant regardless of B. It was revealed that as the field increases, the low-temperature maximum near the 3D-2D transition temperature T0 is blurred and disappears at B > 5 T. Moreover, above the Ginzburg temperature TG, which limits superconducting fluctuations from below, for B > 0.5 T, a minimum appears on Δ*(T) at Tmin, which becomes very pronounced with a further increase in B. As a result, the overall value of Δ*(T) decreases noticeably most likely due to the pair-breaking effect. A comparison of Δ*(T) near Tc with the Peters-Bauer theory shows that the density of fluctuating Cooper pairs actually decreases from ⟨n↑n↓⟩ ≈ 0.31 at B = 0 to ⟨n↑n↓⟩ ≈ 0.28 in the field of 8 T. The observed behavior of Δ*(T) around Tmin is assumed to be due to the influence of a two-dimensional vortex lattice created by the magnetic field, which prevents the formation of fluctuating Cooper pairs near Tc
coherence length. , excess conductivity , fluctuation conductivity , high-temperature superconductors , magnetic field , pseudogap , YBCO films
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B. Verkin Institute for Low Temperature Physics and Engineering, the National Academy of Sciences of Ukraine, Kharkiv, 61103, Ukraine
Institute of Low Temperature and Structural Research, Polish Academy of Sciences, Wroclaw, 50-422, Poland
K. Zhubanov Aktobe Regional State University, Aktobe, 030000, Kazakhstan
Lappeenranta University of Technology, School of Engineering Science, Lappeenranta, 53850, Finland
B. Verkin Institute for Low Temperature Physics and Engineering
Institute of Low Temperature and Structural Research
K. Zhubanov Aktobe Regional State University
Lappeenranta University of Technology
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