RF-Current Effects on Intrinsic Josephson Junctions

We have fabricated intrinsic Josephson junction arrays using Tl
₂
Ba
₂
CaCu
₂
O
₈
thin films. The junctions have dimensions of order 1 mum
²
and therefore high slope resistance in the range 1 kOmega to 10 kOmega per junction on the quasiparticle branches. We have irradiated the junctions with microwaves at a frequency of 6.37 GHz. We observe both microwave-induced vortex-flow branches and strong suppression of the switching current but only when no junctions are in the voltage state. We attribute this observation to the shunting of the high-resistance junctions by the environmental impedance, and discuss the significance of this result for the application of intrinsic junctions as THz sources and qubits.