YBa2Cu3O7minus;dgr;hyphen;Aghyphen;Al/Al2O3/Pb tunnel junctions based on the superconducting proximity effect

摘要

YBa2Cu3O7minus;dgr;hyphen;Aghyphen;Al/Al2O3/Pb superconducting tunnel junctions with high subgap resistance were fabricated using the proximity effect induced superconductivity in the Aghyphen;Al layer by the YBa2Cu3O7minus;dgr;film. At low temperature an energy gap of 9ndash;10 meV is found to be induced in the aluminum layer. Above 20 K the induced gap disappears mainly due to the decreased normal metal coherence length. At higher voltages (Vle;120 meV) the dynamic conductancedI/dVprop;V, characteristic for the normal tunneling density of states of the oxide superconductor.