RESONANT-TUNNELING AND LONG-RANGE PROXIMITY EFFECT

The critical current of SIS tunnel structures in which the primary cur rent-transport mechanism is a resonant tunneling through a single loca lized state is calculated from the Gor'kov equations. The critical cur rent is governed by a competition between tunneling and thermal mechan isms for the decay of a state into a localized.state. The results foun d here agree satisfactorily with experimental data. They explain the a nomalous proximity effect and also the properties of grain-boundary Jo sephson junctions made of high-T(c) superconductors.