The spectral conductance of a proximity superconductor and the reentrance effect

In a mesoscopic metal in proximity, with a superconductor, the electronic c onductance is enhanced in a very energy-sensitive way. In this paper, we di scuss the spectral conductance of a proximity superconductor from both rite theoretical and experimental point of view. The dependence of the spectral conductance on the phase-breaking length, gap of the superconductor and in terface transparency is theoretically investigated. We present experimental data on the reentrance of the normal-state conductance at very low tempera ture and bias voltage. A complete description of the experimental data need s taking into account heating of the reservoirs by the bias current. In add ition, we show that the energy sensitivity of the proximity effect enables one to access the energy distribution of the conduction electrons inside a mesoscopic sample.