Physica C: Superconductivity and its applications

Spectroscopy study of Hg1Ba2Ca2Cu3O8+x by scanning tunneling microscopy

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We have measured the tunnel conductance of sintered Hg-1223 superconductor (Tc onset = 133 K) using a low-temperature STM with Au tips. In spite of spatial fluctuations due to sample surface inhomogeneity gap-like structures are found with Δ ≅ 24 ± 2 mV at 4.2 K. These values remain almost constant up to at least 80 K. The usual background conductance is parabolic, and ohmic in fewer cases. Samples melted under high pressure have also been investigated. © 1994.