We report on tunneling spectra measured on sintered and melted Hg-1223 (Tc onset=133 K) and on single crystals of lead-doped Hg-1234 (Tc onset = 127 K) using a low-temperature scanning tunneling microscope. The conductance curves dI/dV with well-defined gaplike features are usually obtained in the point contact mode, but for the single crystals true noncontact tunneling has also been achieved. From their temperature dependence a scaling between the superconducting gap Delta measured at 4.2 K and an effective transition temperature Tc* of the surface is derived.
By: C. Rossel, P. Bauer, J. Karpinski (ETH, Switz.), A. Schilling (ETH, Switz.) and A. Morawski (High Pressure Res. Ctr., Poland)
Published in: RZ2678 in 1994
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