Comment on “Temperature range of superconducting fluctuations above Tc in YBa2Cu3O7−δ single crystals”

Abstract

Contrary to the starting assumption of Grbić et al. [Phys. Rev. B 83, 144508 (2011)], here we will argue that a 16-T magnetic field is not enough to quench all superconducting fluctuations above Tc in YBa2Cu3O7−δ. We conclude that through their measurements of microwave absorption these authors actually determine the AC fluctuation magnetoconductivity at 16 T, instead of the zero-field AC paraconductivity as they contend. So the temperature proposed by Grbić et al. for the onset of the superconducting fluctuations, T′, will correspond to the one at which the finite-field effects at 16 T become measurable in their experiments and the actual fluctuation onset will be located well above T′. These conclusions, which also concern influential recent publications on that issue, are confirmed by analyzing some of the Grbić et al. data on the grounds of the Gaussian Ginzburg-Landau approach for the finite-field (or Prange) fluctuation regime.

Source-reported materials — not catalogue approval

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