Electron tunneling spectroscopy of single-crystal Bi2Sr2CaCu2O8

H. J. Tao, A. Chang, Farun Lu, and E. L. Wolf
Phys. Rev. B 45, 10622 – Published 1 May 1992
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Abstract

The T-dependent conductance G(V,T) of evaporated Pb junctions on cleaved ab planes of Bi2Sr2CaCu2O8 (2:2:1:2) crystals is presented. Strong superconducting Gs(V,T) structures imply a large gap, approximately Δ0(0)=26 meV, or 2Δ0(0)/kBTc=6.7. An analysis of G(V,T) near Tc, assuming a lifetime-broadened BCS Ns(E), reveals a broadening Γ(T) such that Δ(Tc)≊Γ(Tc)≊2kBTc. The fitted Δ(Tc), unlike typical BCS values, is ≊0.8Δ(0). $G(V,T>T sub c )— has a minimum at V=0, suggestive of known c-direction localization in 2:2:1:2 compounds. G(V,T) also reveals the expected fluctuation superconductivity above Tc. 4.2-K scanning-tunneling-microscope (STM) spectra are mentioned in comparison. A larger gap, about 40 meV, and dip at 80 meV, found in the STM G(V) are tentatively attributed to CuO2 planes.

  • Received 26 November 1991

DOI:https://doi.org/10.1103/PhysRevB.45.10622

©1992 American Physical Society

Authors & Affiliations

H. J. Tao, A. Chang, Farun Lu, and E. L. Wolf

  • Polytechnic University, Brooklyn, New York 11201

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Vol. 45, Iss. 18 — 1 May 1992

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