We have performed transport measurements on bridges patterned in misaligned thin films of the superconductor Tl2Ba2CaCu2O8. There is a c-axis component of current flow along the bridge, giving rise to hysteretic Josephson-like current–voltage curves. The temperature dependence of the critical current follows the Ambegaokar–Baratoff theory with IcRN up to 26 mV at 4.2 K. Microwave emission from the Josephson junctions near Tc (≈103 K) has been detected using an X-band detector. We show that 700±15 junctions in the bridge are actively oscillating, confirming that the junctions are “intrinsic” junctions formed by adjacent copper oxide planes in the Tl2Ba2CaCu2O8 crystal structure.

At the plasma frequency this junction is isolated from its environment and it sees its own large (~ kW) impedance. Our results suggest that stacks of Josephson junctions may be used for isolation purposes in the development of a solid state quantum computer.

We have fabricated sub-micron intrinsic Josephson junctions in thin films of Tl-Ba-Ca-Cu-O using two differing techniques suited to different applications. By using lateral focussed ion-beam milling we have created arrays of intrinsic junctions in -axis oriented films. Such arrays, with areas as low as 0.25 m 2 , display large hysteresis comparable to that observed in single-crystal intrinsic junctions. By using normal focussed ion-beam milling we have created arrays in mis-aligned films grown on vicinal substrates. In arrays of area less than 0.4 m 2 we observe Josephson phase diffusion and a suppressed critical current, showing that charging effects may be significant in these junctions.

We have measured the transport properties of intrinsic Josephson junction arrays as a function of both temperature and magnetic field, the field being applied perpendicular to the transport current. We show that they depend upon whether the junction width exceeds or is less than the Josephson penetration depth. For widths greater than the Josephson penetration depth, the transport properties are dominated by Josephson vortex flow. For widths less than the Josephson penetration depth, the zero-field dissipation is dominated by Josephson phase diffusion. For non-zero applied fields, there is a good fit to the classical “Fraunhofer” dependence of the critical current upon field in addition to a competition between Josephson phase diffusion and Josephson vortex flow.

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