Low Temperature Physics: 28, 17 (2002); https://doi.org/10.1063/1.1449180 (8 pages)
Fizika Nizkikh Temperatur: Volume 28, Number 1 (January 2002), p. 24-35    ( to contents , go back )

Fluctuation conductivity in YBa2Cu3O7-y films of various oxygen content.I.Optimally and weakly doped YBCO films


B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Lenin Ave., 61103 Kharkov, Ukraine
E-mail: solovjov@ilt.kharkov.ua

H.-U.Habermeir,and T.Haage

Max-Planck-Institute für Festkorperforschung,Heisenbergstr.1,70569 Stuttgart,Germany

Received June 6, 2001, revised September 18, 2001


The fluctuation-induced conductivity measured for YBa2Cu3O7-y (YBCO)films of various oxygen concentration is analyzed using different theoretical models describing weak fluctuations in high-Tc superconductors and considering both the Aslamazov-Larkin and Maki-Thompson terms in the clean limit approach.A clear crossover from the MT to AL fluctuation mechanism is revealed for all the samples studied as temperature approaches Tc. Using the crossover temperature T0 the coherence lengh along the c-axis xc(0), and the phase-relaxation time of the fluctuating pairs, tj (100 K), are determined. Despite the fact that Tc decreases from 87.4 down to 54.2 K with oxygen depletion tj (100 K)=(335±0,01)×10-13 s is obtained in all the cases.The xc vs Tc dependence is found to follow the standard superconductivity theory. Possible mechanisms of charge scattering, mainly based on the NAFL model description and of superconducting pairing are also considered.

74.40.+k - Fluctuations (noise, chaos, nonequilibrium superconductivity, localization, etc.)

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