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Influence of strong electron irradiation on fluctuation conductivity and pseudogap in YBa2Cu3O7−δ single crystals

A. L. Solovjov, K. Rogacki, N. V. Shytov, E. V. Petrenko, L. V. Bludova, A. Chroneos, R. V. Vovk

DOI 10.1103/PhysRevB.111.174508 · Physical Review B

T1

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Abstract

The effect of high-energy electron irradiation on the temperature dependences of the resistivity ρ(T), fluctuation conductivity (FLC), and pseudogap (PG) Δ*(T) of YBa2Cu3O7−δ (YBCO) single crystals containing virtually no twins was studied. A linear increase in the resistivity and a linear decrease in the superconducting (SC) transition temperature Tc with increasing irradiation doses φ were observed. For relatively small φ, the linear Tc can be described by the Abrikosov-Gorkov (AG) pair breaking theory, and for large φ, by the Emery-Kivelson (EK) theory, which takes into account the suppression of Tc by quantum phase fluctuations caused by irradiation defects. As FLC shows, at the average value of φ3=2.5×1019e/cm2, which corresponds to the AG-EK crossover, the distance between the conducting CuO2 planes, d01, as well as the coherence lengths along the c axis, ξc(0), and the region of SC fluctuations, ΔTfl, increase sharply, and the two-dimensional contribution of the Maki-Thompson fluctuations (2D-MT) unexpectedly changes to the two-dimensional contribution of the Aslamazov-Larkin (2D-AL). Surprisingly, no features in ρ(φ) and Tc(φ) indicating the AG-EK crossover are observed. At the same time, at φ3, a sharp increase in the opening temperature of PG, T*, as well as the value of PG, Δ*, is observed, which indicates a possible decrease in DOS under the influence of defects. With a further increase in φ, all the parameters of PG and its dimensions are greatly reduced, and an unusual shape of Δ*(T) is found. However, quite unexpectedly, at φ5=5.6×1019e/cm2 the temperature dependences of both FLC and PG demonstrate curves typical for well-structured YBCO, regardless of the number of defects.

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FormulaReported Tc (K)Pressure (GPa)Type
YBa2Cu3O7-δ

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92.5Pressure not reportedzero_resistance

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