Abstract

The authors analysis of in-plane paraconductivity measurements on YBa2Cu3O7-δ (YBCO) films indicates that short-wavelength cutoff effects are significant even very close to the critical point because of the short coherence length ξ. Consequently, the Aslamazov-Larkin (AL) and Lawrence-Doniach expressions are inapplicable to YBCO in the whole Ginzburg-Landau mean-field region, while a generalized AL expression in three-dimensions, that replaces the conventional AL expression in the case of short ξ, accounts for the data within the experimental error. They conclude that the superconducting state of YBCO is three-dimensional and that the universal AL relation between the critical exponent of paraconductivity and the dimensionality of the superconducting fluctuations is no longer valid in superconductors with sufficiently short ξ

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