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Tunneling spectra and superconducting gap in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} and Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}}

Journal Article · · International Journal of Modern Physics B
Tunneling spectra are reported for Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (Bi-2212) over a wide doping range using superconductor-insulator-superconductor (SIS) break junctions. The energy gap inferred from the tunneling data displays a remarkable monotonic dependence on doping, increasing to very large values in the underdoped region even as {Tc} decreases. This leads to unphysically large values of the strong coupling ratio ({approximately}20). The tunneling spectra are qualitatively similar over the entire doping range even though the gap parameter, {Delta}, changes from 12 meV to 60 meV. Each spectrum exhibits dip and hump features at high bias with characteristic energies that scale with the superconducting gap. Tunneling spectra of near optimally-doped Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} (Tl-2202) also display a weak dip feature in superconductor-insulator-normal metal (SIN) junctions. Generated SIS spectra of Tl-2201 are compared with measured spectra on Bi-2212 and it is concluded that the dip and hump features are generic to high temperature superconductors.
Research Organization:
Argonne National Lab., IL (US)
Sponsoring Organization:
US Department of Energy; National Science Foundation
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
20015160
Journal Information:
International Journal of Modern Physics B, Journal Name: International Journal of Modern Physics B Journal Issue: 29-31 Vol. 13; ISSN IJPBEV; ISSN 0217-9792
Country of Publication:
United States
Language:
English