Electrodynamics of closely coupled YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// junctions

Direct electron-beam irradiation of high-T/sub c/ thin films has been used to create closely spaced Josephson junctions which operate at temperatures of 60-80 K. The electrodynamics of two junctions have been investigated by studying the dependence of the critical current on an applied magnetic field. The junctions spaced between 50 and 150 nm could be measured independently by using a narrow third electrode. Closely spaced junctions with moderate critical currents showed a strong divergence of I/sub c/s when a magnetic field was applied. We show that these results correspond with simulations of two junctions coupled by a redistribution current. At higher critical currents the same junctions show locking of their I/sub c/s. We propose a three terminal device based on these closely-spaced multiple junctions.