Absence of pseudogap in heavily overdoped Bi <sub>2</sub> Sr <sub>2</sub> CaCu <sub>2</sub> O <sub>8 + δ</sub> from tunneling spectroscopy of break junctions
L. ÖzyüzerDepartment of Physics, Izmir Institute of Technology - TR-35437 Izmir, TurkeyJ. F. ZasadzinskiMaterials Science Division, Argonne National Laboratory - Argonne IL 60439, USAK. E. GrayMaterials Science Division, Argonne National Laboratory - Argonne IL 60439, USAChristopher A. KendzioraNaval Research Laboratory - Washington DC 20375, USAN. MiyakawaDepartment of Applied Physics, Science University of Tokyo - Tokyo, Japan
2002en
ABI
Аннотация
We report tunneling spectroscopy of superconductor-insulator-superconductor break junctions on heavily overdoped Bi2Sr2CaCu2O8+δ with Tc = 56 K. At T ≪ Tc, 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 Δ = 10.5 meV have been observed leading to 2Δ/kTc near the BCS limit for dx2-y2 pairing. Temperature dependence of the gap magnitude, Δ(T), follows the BCS relation and both the quasiparticle gap and Josephson current vanish for T > Tc. Above Tc, the tunneling conductance shows a flat background without any indication of a pseudogap near the Fermi level.
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