Resistively-shunted Bi2Sr2CaCu2O8+x intrinsic Josephson junctions

Observation of Shapiro steps is probably the most convincing demonstration of the Josephson effects in superconducting weak links. To observe, Shapiro steps in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions (IJJs), we used sid e-wall of gold to resistively-shunt these junctions in a conventional mesa structure. In the current-voltage (I-V) characteristics of these shunted IJ Js, the voltage jumps and the hysteresis were greatly reduced. In particula r, individual Shapiro steps were clearly observed with irradiation up to 10 0 GHz, thus providing direct evidence for the ac Josephson effect in intrin sic high-T-c stack junctions. Also discussed will be the conditions for ach ieving stable phase locking between the external irradiation and internal J osephson oscillation. We believe that resistive shunting of the junction st acks makes it possible for them to be used in on-chip detection or coherent oscillation up to terahertz region. (C) 2001 Elsevier Science B.V. All rig hts reserved.