Some structural and fluctuation properties of superconducting YBCO thin films

Abstract

The characterization of superconducting thin films was performed by starting with x-ray measurements as this is a necessary technique to single out potential superconductors although it is not sufficient to determine superconductivity. The temperature dependence of the paraconductivity can be described by a power law described by the Aslamasov-Larkin theory. A study of the fluctuation conductivity was performed leading to the determination of the coherence length. The values found are compatible with the two-dimensional nature of these new superconductors.

An investigation of superconducting YBCO thin films grown on different substrates

“…In fact we would assign it to Anderson localization [6]. The sample grown on ZrO 2 has metallic properties with resistance decreasing slowly before reaching the onset temperature T onset ∼ 91 K. Prior to the onset, there is a pronounced increase in the positive resistance gradient, the dangers inherent in a fluctuation conductivity analysis [8][9][10] on data from better samples.…”

Fluctuation conductivity and inhomogeneity in granular YBa2Cu3O7−y/Ag composite thick films

“…We have used the derivative of the resistivity data as a function of temperature ( dρ dT ), with T c defined as the peak position of this derivative (figure 1) as has been done by many [8,9,14]. The effect of uncertainty in the determination of the T c results in a temperature range corresponding to the critical region, where the excess conductivity sensitively depends on the reduced temperature [15,16]. The mean field region however remains fairly insensitive to T c uncertainty as shown in figure 2 for one of our samples (YBCO/Ag 5 wt%).…”

“…The AL relation is based on the Ginzburg-Landau (GL) mean field theory and is valid only in a mean field temperature range ∼1.01T c to 1.1T c . The amplitude A is a temperature independent parameter and its value for 2D and 3D cases is e 2 16 hd and e 2 32 hξc(0) respectively, where d and ξ c (0) are the effective layer spacing and the GL correlation length respectively.…”