2003/07/22 by D. -N. Peligrad, D.-N. Peligrad, Michael Mehring +3
Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Superconductivity in MgB2 and Alloys #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.69.144516
10 pages, 27 figures
arxiv created 2003/07/22 · openalex publication_date 2004/04/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Critical fluctuations have been studied in the microwave conductivity of Bi2Sr2CaCu2O_8+\ensuremathδ, Bi2Sr2Ca2Cu3O_10+\ensuremathδ, and YBa2Cu3O_7\ensuremath-\ensuremathδ thin films above Tc. It is found that a consistent analysis of the real and imaginary parts of the fluctuation conductivity can be achieved only if an appropriate wave vector or energy cutoff in the fluctuation spectrum is taken into account. In all of the three underdoped superconducting films one observes strong fluctuations extending far above Tc. The coherence length inferred from the imaginary part of the conductivity exhibits the static critical exponent \ensuremathν=1 very close to Tc, and a crossover to the region with \ensuremathν=2/3 at higher temperatures. In parallel, our analysis reveals the absence of the normal conductivity near Tc, i.e., fully opened pseudogap. Following the crossover to the region with \ensuremathν=2/3, the normal conductivity is gradually recovered, i.e., the closing of the pseudogap is monitored.