Abstract
We have studied superconductor/normal-metal/superconductor junctions consisting of short Au or Cu wires between Nb or Al banks. The Nb based junctions display inherent electron heating effects induced by the high thermal resistance of the boundaries. The Al based junctions show in addition subharmonic gap structures in the differential conductance and a pronounced peak in the excess noise at very low voltages V. We suggest that the noise peak is caused by fluctuations of the supercurrent at the onset of Josephson coupling between the superconducting banks. At intermediate temperatures where the supercurrent is suppressed a noise contribution remains, which suggests the presence of a long-range proximity effect in the noise.
- Received 10 February 2000
DOI:https://doi.org/10.1103/PhysRevB.62.4079
©2000 American Physical Society