Microwave response of YBaCuO/MgO/Pb planar josephson tunnel junctions

Abstract

Microwave response of YBaCuO (YBCO) /MgO/Pb planar Josephson tunnel junctions fabricated by an in situ deposition technique is presented. The observed Josephson critical current is 20–400μA.The current-voltage characterisitcs under microwave irradiation of 9GHz yield the Shapiro steps at integer multiples of hf/2e where f is the microwave frequency. Dependence of the Shapiro step height on the microwave voltage amplitude is consistent with that of the conventional theory. A series of subharmonic steps at half integer multiples of hf/2e are also observable, although their structures are weak.