Josephson nonequilibrium phenomena under current injection in superconducting three-terminal stacked devices

Three-terminal superconducting tunnel devices offer a powerful tool to investigate nonequilibrium phenomena in superconductors. We study the role of the proximity effect in a Nb/Al bilayer forming the intermediate electrode of a stacked structure configuration. The spatial profile of the pair potential along the common electrode and the effective density of states near the detector tunnel barrier are determined by combining the deconvolution of the current-voltage (I-V) injector characteristics and the numerical solution of the microscopic proximity model equations. The Josephson current variation following a steady-state injection was measured down to 1.5 K. Results are discussed in the framework of a simple nonequilibrium model, which leads also to an estimate of the effective relaxation time limiting quasiparticle scattering processes in the Nb/Al bilayer.