Analysis of crossover phenomena in the paraconductivity of YBCO thin films obtained by laser ablation

They present paraconductivity measurements on YBCO thin films obtained by means of pulsed laser ablation in MBE condition. The films, grown in different oxygen pressure, exhibit critical temperatures ranging from 81 to 91 K. The excess conductivity was analyzed in order to study critical phenomena. They observe the Lawrence-Doniach crossover and, at higher temperatures, the crossover related to the breakdown of the Ginzburg-Landau approximation, due to the importance of short wave fluctuations; the first crossover shifts to lower temperatures as the critical temperature of the film decreases, while the second occurs for all the samples roughly at the same reduced temperature, which proves the universality of the paraconductivity behaviour