Anomalous superconducting state gap size versus behavior in underdoped

J. Harris, Z. X. Shen, P. White, D. Marshall, M. Schabel, J. Eckstein, I. Bozovic

Research output: Contribution to journalArticlepeer-review

Abstract

We report angle-resolved photoemission spectroscopy measurements of the excitation gap in underdoped superconducting thin films of Bi2Sr2Ca1-xDyxCu2O 8+δ. As Tc is reduced by a factor of 2 by underdoping, the superconducting state gap Δ does not fall proportionally, but instead stays constant or increases slightly, in violation of the BCS mean-field theory result. The different doping dependences of Δ and kTc indicate that they represent different energy scales. The measurements also show that Δ is highly anisotropic and consistent with a dx2-y2 order parameter, as in previous studies of samples with higher dopings. However, in these underdoped samples, the anisotropic gap persists well above Tc. The existence of a normal state gap is related to the failure of Δ to scale with Tc in theoretical models that predict pairing without phase coherence above Tc.

Original languageEnglish (US)
Pages (from-to)R15665-R15668
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume54
Issue number22
DOIs
StatePublished - 1996
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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