Professor Paolo G. Radaelli OSI

Abstract:

We have realized planar tunnel junctions using both Y123 and Y124 single crystals as base electrodes and Pb as counterelectrode. The crystals, with T c =90 K (Y123) and T c =80 K (Y124), have been chemically etched and natural barriers were formed by a short air exposure. We have compared the tunneling spectra obtained on both systems. The features at about±18mV of the Y123 compound are still observed in the Y124, while the low-bias structures at ±5 mV are not present in the tunneling characteristics of the Y124 system. Linearity of the background conductance is also observed, with less steep slopes in Y124 that might indicate a reduced interlayer coupling in this system. © 1994 Societá Italiana di Fisica.

Abstract:

A cuprate superconductor containing double mercury layers was synthesized with a high-pressure, high-temperature technique. The compound, with chemical formula Hg(2)Ba(2)-Y1-xCaxCu(2)O(8-delta), contains a double HgO layer with structure similar to that of rock salt. The prototype compound Hg(2)Ba(2)YCu(2)O(8-delta) is an insulator. Superconductivity is induced in the system by partially replacing yttrium with calcium.