Superconducting gap and pseudogap for overdoped Bi2−xPbxSr2CaCu2O8+δ using 60ns time-scale short-pulse interlayer tunneling spectroscopy

Abstract

We have measured the interlayer tunneling spectra for overdoped Bi2−xPbxSr2CaCu2O8+δ single crystals with a doping level p ranging from 0.20 to 0.22 and a Tc from 80to67K using a small mesa structure and a 60ns time-scale short-pulse technique. It is found that, with increasing doping, the superconducting gap decreases from 46to18meV, while the pseudogap decreases from 42to10meV. The result indicates the existence of the pseudogap in the overdoped region even at a doping level p higher than 0.19, at which the pseudogap is expected to disappear in some generic phase diagram models. Furthermore, the values obtained for the superconducting gap, normal tunneling resistance, and the maximum Josephson current indicate the likeliness of the inhomogeneous superconducting state even in the overdoped region.

Source-reported materials — not catalogue approval

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