Volume 58, Number 4, May 2002
|Page(s)||589 - 595|
|Section||Condensed matter: electronic structure, electrical, magnetic, and optical properties|
|Published online||01 May 2002|
Absence of pseudogap in heavily overdoped from tunneling spectroscopy of break junctions
Materials Science Division, Argonne National
Laboratory - Argonne IL 60439, USA
2 Department of Physics, Izmir Institute of Technology - TR-35437 Izmir, Turkey
3 Physics Division, Illinois Institute of Technology - Chicago IL 60616, USA
4 Naval Research Laboratory - Washington DC 20375, USA
5 Department of Applied Physics, Science University of Tokyo - Tokyo, Japan
Accepted: 21 February 2002
We report tunneling spectroscopy of superconductor-insulator-superconductor break junctions on heavily overdoped Bi2Sr2CaCu2O with K. At , the junction conductances display well-defined quasiparticle peaks at ±2Δ and in some cases a Josephson current at zero bias. Gap values as small as meV have been observed leading to 2 near the BCS limit for pairing. Temperature dependence of the gap magnitude, , follows the BCS relation and both the quasiparticle gap and Josephson current vanish for . Above , the tunneling conductance shows a flat background without any indication of a pseudogap near the Fermi level.
PACS: 74.72.-h – High- compounds / 74.50.+r – Proximity effects, weak links, tunneling phenomena, and Josephson effects / 74.62.Dh – Effects of crystal defects, doping and substitution
© EDP Sciences, 2002
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