Observation of a New Superconducting State at High Quasiparticle Injection

The behavior of a superconducting A1 film under conditions of large nonequilibrium injection of quasiparticles is studied by means of a tunnel generator and detector. At a critical injection density, $n_c$, a second energy gap develops in the superconductor. The relevance to recent theories of nonequilibrium superconductivity is discussed.