Critical fluctuations and pseudogap observed in the microwave conductivity of BSCCO and YBCO thin films

Abstract

Critical fluctuations have been studied in the microwave conductivity of Bi_2Sr_2CaCu_2O_(8+δ), Bi_2Sr_2Ca_2Cu_3O_(10+delta), and YBa_2Cu_3O_(7-delta) thin films above T_c. It is found that a consistent analysis of the real and imaginary parts of the fluctuation conductivity can be achieved only if an appropriate wavevector 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 T_c. The coherence length inferred from the imaginary part of the conductivity exhibits the static critical exponent nu = 1 very close to T_c, and a crossover to the region with nu = 2/3 at higher temperatures. In parallel, our analysis reveals the absence of the normal conductivity near T_c, i.e. fully opened pseudogap. Following the crossover to the region with nu = 2/3, the normal conductivity is gradually recovered, i.e. the closing of the pseudogap is monitored.

10 pages, 27 figures

References in corpus (7)

• The onset of the vortex-like Nernst signal above Tc in La_{2-x}Sr_xCuO_4 and Bi_2Sr_{2-y}La_yCuO_6
• Phase fluctuations and the pseudogap in YBa2Cu3Ox
• Critical dynamics of superconducting BSCCO films
• Finite size effect in Bi2Sr2CaCu2O(8+d) and YBa2Cu3O6.7 probed by the in-plane and out of plane penetration depths
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• Frequency-dependent fluctuational conductivity above Tc in anisotropic superconductors: effects of a short wavelength cutoff
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Cited by in corpus (6)

• Temperature range of superconducting fluctuations above T_c in YBa_2Cu_3O_{7-δ} single crystals
• Universal critical behavior in single crystals and films of YBa${}_2$Cu${}_3$O${}_{7-\delta }$
• Dynamical scaling of $YB{a}_{2}C{u}_3{O}_{7-\delta }$ thin film conductivity in zero field
• DC and high-frequency conductivity of the organic metals beta"-(BEDT-TTF)2SF5RSO3 (R = CH2CF2 and CHF)
• Comment on "High Field Studies of Superconducting Fluctuations in High-Tc Cuprates. Evidence for a Small Gap distinct from the Large Pseudogap"
• Effects of Self-field and Low Magnetic Fields on the Normal-Superconducting Phase Transition